United States v. Tsarnaev

(Slip Opinion) OCTOBER TERM, 2021 1

Syllabus

NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
being done in connection with this case, at the time the opinion is issued.
The syllabus constitutes no part of the opinion of the Court but has been
prepared by the Reporter of Decisions for the convenience of the reader.
See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.

SUPREME COURT OF THE UNITED STATES

Syllabus

UNITED STATES v. TSARNAEV

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
THE FIRST CIRCUIT

No. 20–443. Argued October 13, 2021—Decided March 4, 2022
On April 15, 2013, brothers Dzhokhar and Tamerlan Tsarnaev planted
and detonated two homemade pressure-cooker bombs near the finish
line of the Boston Marathon, killing three and wounding hundreds.
Three days later, as investigators began to close in, the brothers fled.
In the process, they murdered a Massachusetts Institute of Technology
campus police officer, carjacked a graduate student, and fought a
street battle with police during which Dzhokhar inadvertently ran
over and killed Tamerlan. Dzhokhar eventually abandoned the vehicle
and hid in a covered boat being stored in a nearby backyard. He was
arrested the following day.
Dzhokhar was indicted for 30 crimes, including 17 capital offenses.
To prepare for jury selection, the parties proposed a 100-question
screening form, which included several questions regarding whether
media coverage may have biased prospective jurors. The District
Court declined to include a proposed question that asked each prospec-
tive juror to list the facts he had learned about the case from the media
and other sources. According to the District Court, the question was
too “unfocused” and “unguided.” Following three weeks of in-person
questioning, a jury was seated. The jury found Dzhokhar guilty on all
counts, and the Government sought the death penalty.
At sentencing, Dzhokhar sought mitigation based on the theory that
Tamerlan had masterminded the bombing and pressured Dzhokhar to
participate. In an attempt to show Tamerlan’s domineering nature,
Dzhokhar sought to introduce the statements of Ibragim Todashev,
who had alleged during an FBI interview that, years earlier, Tamerlan
had participated in a triple homicide in Waltham, Massachusetts. The
Government asked the trial court to exclude any reference to the Wal-
2 UNITED STATES v. TSARNAEV

Syllabus

tham murders on the grounds that the evidence either lacked rele-
vance or, alternatively, lacked probative value and was likely to con-
fuse the issues. The Government also pointed out that, because FBI
agents had killed Todashev in self-defense after he attacked them dur-
ing the interview, there were no living witnesses to the Waltham mur-
ders. The District Court excluded the evidence, and the jury concluded
that 6 of Dzhokhar’s crimes warranted the death penalty.
The Court of Appeals vacated Dzhokhar’s capital sentences on two
grounds. First, the court held that the District Court abused its dis-
cretion during jury selection by declining to ask about the kind and
degree of each prospective juror’s media exposure, as required by that
court’s decision in Patriarca v. United States, 402 F. 2d 314. Second,
the court held that the District Court abused its discretion during sen-
tencing when it excluded evidence concerning Tamerlan’s possible in-
volvement in the Waltham murders.
Held: The Court of Appeals improperly vacated Dzhokhar’s capital sen-
tences. Pp. 8–20.
(a) The District Court did not abuse its discretion by declining to ask
about the content and extent of each juror’s media consumption re-
garding the bombings. Jury selection falls “particularly within the
province of the trial judge,” Skilling v. United States, 561 U. S. 358,
386, whose broad discretion in this area includes deciding what ques-
tions to ask prospective jurors, see Mu’Min v. Virginia, 500 U. S. 415,
427. Here, the District Court did not abuse that discretion when, rec-
ognizing the significant pretrial publicity concerning the bombings, the
court refused to allow the question at issue because it wrongly empha-
sized what a juror knew before coming to court, rather than potential
bias. That decision was reasonable and well within the court’s discre-
tion.
The rest of the jury-selection process in this case dispels any remain-
ing doubt. The District Court used the 100-question juror form—which
asked prospective jurors what media sources they followed and
whether any of that information had caused them to form an opinion
about Dzhokhar’s guilt or punishment—to cull down the number of
prospective jurors. The District Court then subjected those remaining
prospective jurors to three weeks of individualized voir dire, including
questions that probed for bias. Finally, the court instructed the pro-
spective jurors during voir dire, and the seated jurors during trial, that
their decisions must be based on the evidence presented at trial and
not any other source.
The Court of Appeals erred when it concluded that the District Court
abused its discretion by failing to put Dzhokhar’s proposed media-con-
tent question to the jury. Following its decision in Patriarca, the court
concluded that it had “supervisory authority” to require the District
 Cite as: 595 U. S. ____ (2022) 3

Syllabus

Court, as a matter of law, to ask the jurors that specific question. The
supervisory power of federal courts, however, does not extend to the
creation of prophylactic supervisory rules that circumvent or supple-
ment legal standards set out in decisions of this Court. See United
States v. Payner, 447 U. S. 727, 733–737. Pp. 8–13.
(b) Nor did the District Court abuse its discretion in excluding from
the sentencing proceedings evidence of the Waltham murders. The
Federal Death Penalty Act provides that, at the sentencing phase of a
capital trial, “information may be presented as to any matter relevant
to the sentence, including any mitigating or aggravating factor.” 18
U. S. C. §3593(c). But the district court may exclude information “if
its probative value is outweighed by the danger of creating unfair prej-
udice, confusing the issues, or misleading the jury.” Ibid. Such evi-
dentiary decisions are reviewed for abuse of discretion. See United
States v. Abel, 469 U. S. 45, 54. Here, Dzhokhar sought to introduce
evidence linking Tamerlan to the unsolved Waltham murders to sup-
port his mitigation defense that Tamerlan was the ringleader of the
bombing. That evidence, however, did not allow the jury to confirm or
assess Tamerlan’s alleged role in the Waltham murders. The District
Court did not abuse its discretion when it reasonably excluded the ev-
idence for its lack of probative value and potential to confuse the jury.
Dzhokhar’s counterarguments are unconvincing. First, §3593(c) does
not violate the Eighth Amendment. That provision falls well within
the the Federal Government’s “ ‘traditional authority’ ” “to decide that
certain types of evidence may have insufficient probative value to jus-
tify their admission,” Skipper v. South Carolina, 476 U. S. 1, 11, 15
(Powell, J., concurring in judgment), and “to set reasonable limits upon
the evidence a [capital] defendant can submit, and control the manner
in which it is submitted,” Oregon v. Guzek, 546 U. S. 517, 526. Section
3593(c) sets up a highly permissive regime that allows criminal de-
fendants to introduce a wide range of normally inadmissible evidence
and channels that evidence through an individualized balancing test
that affords a capital defendant every reasonable opportunity to place
relevant mitigation evidence before the penalty-phase jury. Here, the
bare inclusion of the Waltham-murders evidence risked producing a
confusing mini-trial where the only witnesses who knew the truth
were dead. That the evidence excluded by the District Court was con-
sidered reliable enough to include in a search warrant has no bearing
here, where the District Court was free to evaluate the information
independently when deciding whether to admit it under §3593(c).
The dissent recognizes that the District Court enjoyed significant
discretion over its evidentiary decisions. But because this is a death
penalty case, the dissent scrutinizes those decisions with particular
care to find that the District Court abused its discretion. In doing so,
4 UNITED STATES v. TSARNAEV

Syllabus

the dissent ignores the traditional abuse-of-discretion standard, which
calls for a reviewing court to defer to the sound judgment of a district
court unless the decision was “manifestly erroneous.” General Elec.
Co. v. Joiner, 522 U. S. 136, 142. More specifically, the dissent sug-
gests that a district court presiding over death-penalty proceedings
should be more hesitant to find that evidence risked confusing the jury.
But nothing in §3593(c) suggests that Congress intended for any such
hesitancy. Ultimately, the District Court reasonably decided to ex-
clude the evidence under §3593(c)’s balancing test. Pp. 13–20.
968 F. 3d 24, reversed.

THOMAS, J., delivered the opinion of the Court, in which ROBERTS, C. J.,
and ALITO, GORSUCH, KAVANAUGH, and BARRETT, JJ., joined. BARRETT,
J., filed a concurring opinion, in which GORSUCH, J., joined. BREYER, J.,
filed a dissenting opinion, in which SOTOMAYOR and KAGAN, JJ., joined
except as to Part II–C.
 Cite as: 595 U. S. ____ (2022) 1

Opinion of the Court

NOTICE: This opinion is subject to formal revision before publication in the
preliminary print of the United States Reports. Readers are requested to
notify the Reporter of Decisions, Supreme Court of the United States, Wash-
ington, D. C. 20543, of any typographical or other formal errors, in order that
corrections may be made before the preliminary print goes to press.

SUPREME COURT OF THE UNITED STATES
_________________

No. 20–443
_________________

UNITED STATES, PETITIONER v.
DZHOKHAR A. TSARNAEV
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE FIRST CIRCUIT
[March 4, 2022]

JUSTICE THOMAS delivered the opinion of the Court.
On April 15, 2013, Dzhokhar and Tamerlan Tsarnaev
planted and detonated two homemade pressure-cooker
bombs near the finish line of the Boston Marathon. The
blasts hurled nails and metal debris into the assembled
crowd, killing three while maiming and wounding hun-
dreds. Three days later, the brothers murdered a campus
police officer, carjacked a graduate student, and fired on po-
lice who had located them in the stolen vehicle. Dzhokhar
attempted to flee in the vehicle but inadvertently killed
Tamerlan by running him over. Dzhokhar was soon ar-
rested and indicted.
A jury found Dzhokhar guilty of 30 federal crimes and
recommended the death penalty for 6 of them. The District
Court accordingly sentenced Dzhokhar to death. The Court
of Appeals vacated the death sentence. We now reverse.
I
A
The Tsarnaev brothers immigrated to the United States
in the early 2000s and lived in Massachusetts. Little more
than a decade later, they were actively contemplating how
2 UNITED STATES v. TSARNAEV

Opinion of the Court

to wage radical jihad. They downloaded and read al Qaeda
propaganda, and, by December of 2012, began studying an
al Qaeda guide to bomb making.
On April 15, 2013, the brothers went to the Boston Mar-
athon finish line on Boylston Street. They each brought a
backpack containing a homemade pressure-cooker bomb
packed with explosives inside a layer of nails, BBs, and
other metal scraps. Tamerlan left his backpack in a crowd
of spectators and walked away. Dzhokhar stood with his
backpack outside the Forum, a nearby restaurant where
spectators watched the runners from the sidewalk and din-
ing patio. For four minutes, Dzhokhar surveyed the crowd.
After speaking with Tamerlan by phone, Dzhokhar left his
backpack among the spectators. Tamerlan then detonated
his bomb. While the crowd at the Forum looked toward the
explosion, Dzhokhar walked the other way. After a few sec-
onds, he detonated his bomb.
Each detonation sent fire and shrapnel in all directions.
The blast from Tamerlan’s bomb shattered Krystle Camp-
bell’s left femur and mutilated her legs. Though bystanders
tried to save her, she bled to death on the sidewalk. Dzho-
khar’s bomb ripped open the legs of Boston University stu-
dent Lingzi Lu. Rescuers tried to stem the bleeding by us-
ing a belt as a makeshift tourniquet. She too bled to death.
Eight-year-old Martin Richard absorbed the full blast of
Dzhokhar’s bomb. BBs, nails, and other metal fragments
shot through his abdomen, cutting through his aorta, spinal
cord, spleen, liver, pancreas, left kidney, and large intes-
tines. The blast propelled shrapnel with such force that it
exited his back. Other shrapnel nearly severed his left
hand. The explosion also caused third-degree burns. Mar-
tin ultimately died from blood loss.
Dzhokhar’s and Tamerlan’s bombs maimed and wounded
hundreds of other victims. Many people lost limbs, includ-
ing Martin’s 6-year-old sister, Jane. Many more would
 Cite as: 595 U. S. ____ (2022) 3

Opinion of the Court

have died if not for the swift action of citizens and first re-
sponders.
After fleeing the scene, the brothers returned to their nor-
mal lives. Dzhokhar attended his college classes the next
day. He went to the gym with friends. He posted online
that he was “a stress free kind of guy.” App. 145. Several
days later, on April 18, after the Federal Bureau of Investi-
gation (FBI) released images of the suspected bombers, a
friend saw the images and texted Dzhokhar. Dzhokhar re-
sponded: “Better not text me my friend. Lol.” Id., at 146.
Recognizing that investigators were closing in on them,
Dzhokhar met up with Tamerlan that evening. The broth-
ers collected more homemade bombs and a handgun and
loaded them into Tamerlan’s car. While driving past the
Massachusetts Institute of Technology, they saw 27-year-
old campus police officer Sean Collier sitting in his patrol
car. They approached his car and shot him five times at
close range, including once between the eyes. With Collier
dead, the brothers tried to steal his service pistol but were
unable to remove it from the holster. They then carjacked
and robbed another man, Dun Meng, who was driving his
SUV home from work. When the brothers forced Meng to
stop at a gas station for fuel and snacks, he fled on foot. The
brothers briefly chased him but gave up and made off with
Meng’s SUV.
Meng contacted the police, who used the SUV’s GPS de-
vice to track the Tsarnaevs. When officers found the broth-
ers in Watertown a few hours later, a street battle ensued.
Tamerlan fired on the officers with a handgun, while Dzho-
khar threw homemade bombs. When Tamerlan’s handgun
ran out of ammunition, officers subdued him. As they tried
to handcuff Tamerlan, Dzhokhar returned to the SUV and
sped towards the officers. They evaded the SUV. Tamerlan
did not. Dzhokhar ran over Tamerlan and dragged him
roughly 30 feet down the road. Tamerlan disentangled
from the undercarriage when Dzhokhar rammed a police
4 UNITED STATES v. TSARNAEV

Opinion of the Court

cruiser before escaping. Tamerlan died soon after from his
injuries.
Dzhokhar abandoned the SUV a few blocks away. He
found a covered boat in a nearby backyard. Taking shelter
inside, he carved the words “stop killing our innocent peo-
ple, and we will stop” into the planking. Id., at 151. He also
wrote a manifesto in pencil on the bulkhead of the boat’s
cockpit justifying his actions and welcoming his expected
martyrdom. The next day, the boat’s owner found him. Po-
lice eventually forced Dzhokhar out of the boat and arrested
him.
B
A federal grand jury indicted Dzhokhar for 30 crimes, 17
of which were capital offenses. In preparation for jury se-
lection, the parties jointly proposed a 100-question form to
screen the prospective jurors. The District Court adopted
almost all of them, including many that probed for bias. For
example, some of the District Court’s questions asked
whether a prospective juror had a close association with law
enforcement. Others asked whether a prospective juror had
strong feelings about Islam, Chechens, or the several Cen-
tral Asian regions with which the Tsarnaevs were con-
nected. Still others asked whether the prospective juror
had a personal connection to the bombing.
Several questions also probed whether media coverage
might have biased a prospective juror. One question asked
if the prospective juror had “formed an opinion” about the
case because of what he had “seen or read in the news me-
dia.” App. to Pet. for Cert. 373a. Others asked about the
source, amount, and timing of the person’s media consump-
tion. Still another asked whether the prospective juror had
commented or posted online about the bombings.
The District Court did reject one media-related question.
The proposed questionnaire had asked each prospective ju-
ror to list the facts he had learned about the case from the
 Cite as: 595 U. S. ____ (2022) 5

Opinion of the Court

media and other sources. Concerned that such a broad, “un-
focused” question would “cause trouble” by producing “un-
manageable data” of minimal value that would come to
dominate the entire voir dire, the District Court declined to
include it in the questionnaire. App. 480–481. After Dzho-
khar objected to the removal, the District Court further ex-
plained that the question was “too unguided.” Id., at 486.
Recognizing the intense public interest in the case, the
District Court summoned an expanded jury pool. In early
January 2015, the court called 1,373 prospective jurors for
the first round of jury selection. After reviewing their an-
swers to the questionnaire, the court reduced the pool to
256. As jury selection began in earnest, Dzhokhar renewed
his request that the court ask each juror about the content
of the media he had consumed. The District Court again
refused Dzhokhar’s blanket request and instead permitted
counsel to ask appropriate followup questions about a pro-
spective juror’s media consumption based on the answers to
questions in the questionnaire or at voir dire. Several
times, the court permitted Dzhokhar’s attorneys to follow
up on a prospective juror’s earlier answers with specific
questions about what the juror had seen or heard in the
news. Over the course of three weeks of in-person question-
ing, the District Court and the parties reduced the 256 pro-
spective jurors down to 12 seated jurors.
After the District Court seated the jury, the case went to
trial. Dzhokhar did not contest his guilt and the jury thus
returned a guilty verdict on all counts. During the sentenc-
ing phase, the Government argued that Dzhokhar’s crimes
warranted the death penalty. Dzhokhar’s mitigation the-
ory centered on the idea that Tamerlan masterminded the
bombing. According to Dzhokhar, he was not sufficiently
culpable to warrant the death penalty because his older
brother had pressured him to participate.
To prove Tamerlan’s domineering nature, Dzhokhar
sought to introduce hearsay evidence of a crime Tamerlan
6 UNITED STATES v. TSARNAEV

Opinion of the Court

allegedly had committed years earlier. Specifically, FBI
agents investigating the bombings had come to suspect that
Tamerlan’s friend, Ibragim Todashev, possessed infor-
mation about an unsolved triple homicide in Waltham,
Massachusetts, where a non-Muslim acquaintance of Tam-
erlan’s and two others were found bound, robbed, and mur-
dered with a knife. When agents went to interview
Todashev about a month after the bombings, Todashev ini-
tially denied any involvement. Yet, when pressed, he told
the agents that Tamerlan had hatched a plan to rob the
three Waltham victims of drug proceeds on the night of Sep-
tember 11, 2011. According to Todashev, he and Tamerlan
traveled to Waltham, held the men at gunpoint, and duct-
taped their hands, feet, and mouths. After taking the
money, Tamerlan insisted on killing the three men. Accord-
ing to Todashev, after he disagreed, Tamerlan told him to
wait outside while Tamerlan cut their throats with a knife.
The agents offered Todashev a pen and paper to write out
his confession. Todashev instead attacked the agents, who
killed him in self-defense. The FBI later used Todashev’s
statement to obtain a search warrant for a follow-on search
of Tamerlan’s car.
In the lead-up to trial, the prosecution told Dzhokhar’s
counsel what Todashev had said but did not turn over the
recording of the interview or the FBI reports. The prosecu-
tion also disclosed that Dias Kadyrbayev, a friend of Dzho-
khar’s facing federal obstruction charges in connection with
the bombing, told the investigators that Dzhokhar knew
about Tamerlan’s involvement in the murders. Meanwhile,
Government analysts found evidence that someone had
searched for information about the Waltham murders from
Tamerlan’s wife’s computer a week after they took place.
Government investigators also found jihadi propaganda ad-
vocating theft from non-Muslim “infidels.” Id., at 639.
Before trial, Dzhokhar filed a motion to compel produc-
 Cite as: 595 U. S. ____ (2022) 7

Opinion of the Court

tion of the evidence, which the court denied. The Govern-
ment filed a motion in limine to exclude any reference to
the Waltham murders, contending that the evidence was
irrelevant, or at least so lacking in probative value and so
likely to confuse the issues that the court should exclude it.
The District Court granted the Government’s motion in
limine. As the District Court saw things, the evidence did
not show what Tamerlan’s role was and, with Todashev
dead, no further line of inquiry remained. The available
information was “without any probative value” and “would
be confusing to the jury and a waste of time.” Id., at 650.
When the sentencing proceedings finished, the jury con-
cluded that Dzhokhar warranted the death penalty for 6 of
the 17 death-penalty-eligible crimes, despite Dzhokhar’s ar-
gument that Tamerlan was more culpable. The District
Court accordingly sentenced Dzhokhar to death.
C
The Court of Appeals vacated Dzhokhar’s capital sen-
tence on two grounds. See 968 F. 3d 24, 35 (CA1 2020).
First, the Court of Appeals held that the District Court
abused its discretion during jury selection by declining to
ask every prospective juror what he learned from the media
about the case. Id., at 54–62. According to the panel, such
questions were required by that court’s 1968 decision in Pa-
triarca v. United States, 402 F. 2d 314 (CA1), which had
mandated this voir dire rule “in the exercise of [the court of
appeals’] discretionary supervisory powers, not as a matter
of constitutional law.” 968 F. 3d, at 60. The Court of Ap-
peals ruled that the District Court’s failure to comply with
Patriarca was “an error of law and so an abuse of discre-
tion.” 968 F. 3d, at 59. Second, the panel held that the
District Court abused its discretion when it excluded from
sentencing the evidence concerning Tamerlan’s possible in-
volvement in the Waltham murders. Id., at 63–73. The
panel believed that the evidence was sufficiently probative
8 UNITED STATES v. TSARNAEV

Opinion of the Court

of Tamerlan’s ability to influence Dzhokhar. Id., at 69–70.
We granted certiorari, 592 U. S. ___ (2021).
II
The Government argues that the Court of Appeals im-
properly vacated Dzhokhar’s capital sentences based on the
juror questionnaire and the Waltham evidence. We agree.
A
The Sixth Amendment guarantees “the accused” the
right to a trial “by an impartial jury.” The right to an “im-
partial” jury “does not require ignorance.” Skilling v.
United States, 561 U. S. 358, 381 (2010). Notorious crimes
are “almost, as a matter of necessity, brought to the atten-
tion” of those informed citizens who are “best fitted” for jury
duty. Reynolds v. United States, 98 U. S. 145, 155–156
(1879). A trial court protects the defendant’s Sixth Amend-
ment right by ensuring that jurors have “no bias or preju-
dice that would prevent them from returning a verdict ac-
cording to the law and evidence.” Connors v. United States,
158 U. S. 408, 413 (1895).
We have repeatedly said that jury selection falls “ ‘partic-
ularly within the province of the trial judge.’ ” Skilling, 561
U. S., at 386 (quoting Ristaino v. Ross, 424 U. S. 589, 595
(1976)); see also, e.g., Mu’Min v. Virginia, 500 U. S. 415, 424
(1991); Connors, 158 U. S., at 413. That is so because a trial
“judge’s appraisal is ordinarily influenced by a host of fac-
tors impossible to capture fully in the record,” such as a
“prospective juror’s inflection, sincerity, demeanor, candor,
body language, and apprehension of duty.” Skilling, 561
U. S., at 386. A trial court’s broad discretion in this area
includes deciding what questions to ask prospective jurors.
See Mu’min, 500 U. S., at 427 (“our own cases have stressed
the wide discretion granted to the trial court in conducting
voir dire in the area of pretrial publicity”).
A court of appeals reviews the district court’s questioning
 Cite as: 595 U. S. ____ (2022) 9

Opinion of the Court

of prospective jurors only for abuse of discretion. See, e.g.,
Skilling, 561 U. S., at 387, n. 20; Mu’Min, 500 U. S., at 427;
Rosales-Lopez v. United States, 451 U. S. 182, 189 (1981)
(plurality opinion); Ristaino, 424 U. S., at 594; Ham v.
South Carolina, 409 U. S. 524, 527 (1973); Connors, 158
U. S., at 413. That discretion does not vanish when a case
garners public attention. Indeed, “[w]hen pretrial publicity
is at issue, ‘primary reliance on the judgment of the trial
court makes [especially] good sense.’ ” Skilling, 561 U. S.,
at 386 (quoting Mu’Min, 500 U. S, at 427; alteration in Skil-
ling). After all, “the judge ‘sits in the locale where the pub-
licity is said to have had its effect’ and may base her evalu-
ation on her ‘own perception of the depth and extent of news
stories that might influence a juror.’ ” Ibid. (quoting
Mu’Min, 500 U. S., at 427). Because conducting voir dire is
committed to the district court’s sound discretion, there is
no blanket constitutional requirement that it must ask each
prospective juror what he heard, read, or saw about a case
in the media. Mu’Min, 500 U. S., at 417. Instead, as in any
case, the district court’s duty is to conduct a thorough jury-
selection process that allows the judge to evaluate whether
each prospective juror is “to be believed when he says he
has not formed an opinion about the case.” Id., at 425.
The District Court did not abuse its broad discretion by
declining to ask about the content and extent of each juror’s
media consumption regarding the bombings. The court rec-
ognized the significant pretrial publicity concerning the
bombings, and reasonably concluded that the proposed
media-content question was “unfocused,” risked producing
“unmanageable data,” and would at best shed light on “pre-
conceptions” that other questions already probed. App.
480–481. At voir dire, the court further explained that it
did not want to be “too tied to a script” because “[e]very ju-
ror is different” and had to be “questioned in a way that
[was] appropriate” to the juror’s earlier answers. Id., at
10 UNITED STATES v. TSARNAEV

Opinion of the Court

498. The court was concerned that a media-content ques-
tion had “the wrong emphasis,” focusing on what a juror
knew before coming to court, rather than on potential bias.
Id., at 502. Based on “years” of trial experience, the court
concluded that jurors who came in with some prior
knowledge would still be able to act impartially and “hold
the government to its proof.” Id., at 502–503. The District
Court’s decision was reasonable and well within its discre-
tion, as our precedents make clear. See Mu’Min, 500 U. S.,
at 427.
If any doubt remained, the rest of the jury-selection pro-
cess dispels it. The District Court summoned an expanded
jury pool of 1,373 prospective jurors and used the 100-
question juror form to cull that down to 256. The question-
naire asked prospective jurors what media sources they fol-
lowed, how much they consumed, whether they had ever
commented on the bombings in letters, calls, or online
posts, and, most pointedly, whether any of that information
had caused the prospective juror to form an opinion about
Dzhokhar’s guilt or punishment. The court then subjected
those 256 prospective jurors to three weeks of individual-
ized voir dire in which the court and both parties had the
opportunity to ask additional questions and probe for bias.
Dzhokhar’s attorneys asked several prospective jurors what
they had heard, read, or seen about the case in the media.
The District Court also provided “ ‘emphatic and clear in-
structions on the sworn duty of each juror to decide the is-
sues only on evidence presented in open court.’ ” Skilling,
561 U. S., at 388, n. 21 (quoting Nebraska Press Assn. v.
Stuart, 427 U. S. 539, 564 (1976)). The court reminded the
prospective jurors that they “must be able to decide the is-
sues in the case based on the information or evidence that
is presented in the course of the trial, not on information
from any other sources,” App. 283, an instruction the court
gave during voir dire and repeated during the trial. In sum,
 Cite as: 595 U. S. ____ (2022) 11

Opinion of the Court

the court’s jury selection process was both eminently rea-
sonable and wholly consistent with this Court’s precedents.
The Court of Appeals erred in holding otherwise. As it
saw things, its decision nearly 50 years prior in Patriarca
had, pursuant to its “supervisory authority,” required dis-
trict courts presiding over high-profile cases to ask about
the “ ‘kind and degree of [the prospective juror’s] exposure
to the case or the parties.’ ” 968 F. 3d, at 57 (quoting Patri-
arca, 402 F. 2d, at 318; emphasis deleted). And because Pa-
triarca purportedly set forth a “rule,” the District Court’s
failure to follow it was “an error of law and so an abuse of
discretion.” 968 F. 3d, at 59.
It is true that some of our precedents describe a “supervi-
sory authority” that inheres in federal courts. See, e.g.,
McNabb v. United States, 318 U. S. 332, 343–345 (1943);
Cupp v. Naughten, 414 U. S. 141, 146 (1973).1 But the
Court’s precedents have also identified clear limits when
lower courts have purported to invoke that authority. For
example, supervisory rules cannot conflict with or circum-
vent a constitutional provision or federal statute. Thomas
v. Arn, 474 U. S. 140, 148 (1985). Nor can they conflict with
or circumvent a Federal Rule. Carlisle v. United States, 517
U. S. 416, 426 (1996). Finally, and most relevant here,
lower courts cannot create prophylactic supervisory rules
that circumvent or supplement legal standards set out in
——————
1 Some jurists have questioned this Court’s supervisory authority over

lower courts. See, e.g., Western Pacific R. Corp. v. Western Pacific R. Co.,
345 U. S. 247, 273 (1953) (Jackson, J., dissenting) (questioning “this
Court’s exercise of its vague supervisory powers over federal courts”);
Bank of Nova Scotia v. United States, 487 U. S. 250, 264 (1988) (Scalia,
J., concurring) (“I do not see the basis for any direct authority to super-
vise lower courts”). Others have questioned whether the courts of appeals
enjoy the same power. See, e.g., United States v. Strothers, 77 F. 3d 1389,
1397–1399 (CADC 1996) (Sentelle, J., concurring). The Government
does not challenge the general existence of the Court of Appeals’ super-
visory power. See Tr. of Oral Arg. 11. Hence, we need not address that
issue here.
12 UNITED STATES v. TSARNAEV

Opinion of the Court

decisions of this Court. United States v. Payner, 447 U. S.
727, 733–737 (1980).
Payner exemplifies this last limit. There, a Federal Dis-
trict Court asserted supervisory power to suppress illegally
seized evidence even when the seizure violated a third
party’s Fourth Amendment rights, and the Court of Appeals
affirmed the decision. Id., at 733. This Court reversed, ex-
plaining that its Fourth Amendment jurisprudence had “es-
tablished beyond any doubt” that a defendant could not as-
sert a third party’s Fourth Amendment injury in order to
suppress evidence. Id., at 735. “Were we to accept this use
of the supervisory power,” the Court reasoned, “we would
confer on the judiciary discretionary power to disregard the
considered limitations of the law it is charged with enforc-
ing.” Id., at 737. Simply put, “the supervisory power does
not extend so far.” Ibid.
Nor does any supervisory power extend as the Court of
Appeals appears to suggest in this case. This Court has
held many times that a district court enjoys broad discre-
tion to manage jury selection, including what questions to
ask prospective jurors. See, e.g., Skilling, 561 U. S., at 387,
n. 20; Mu’Min, 500 U. S., at 427; Ristaino, 424 U. S., at 594;
Ham, 409 U. S., at 527; Connors, 158 U. S., at 413. As the
Court of Appeals acknowledged, our cases establish that a
reviewing court may set aside a district court’s questioning
only for an abuse of discretion. See 968 F. 3d, at 56. The
Court of Appeals declined to apply that settled standard of
review. Rather than ask whether media-content questions
were necessary in light of the District Court’s exhaustive
voir dire, the Court of Appeals resurrected Patriarca,
handed down a purported legal rule that media-content
questions are required in all high-profile cases, and then
concluded that the District Court committed a legal error
when it failed to comply with that rule. See 968 F. 3d, at
57–59. But a court of appeals cannot supplant the district
court’s broad discretion to manage voir dire by prescribing
 Cite as: 595 U. S. ____ (2022) 13

Opinion of the Court

specific lines of questioning, and thereby circumvent a well-
established standard of review. Whatever the “supervisory
power” entails, it does not countenance the Court of Ap-
peals’ use of it.
B
The Court of Appeals’ second reason for vacating Dzho-
khar’s capital sentences—that the District Court erred in
excluding from the sentencing proceedings evidence of the
Waltham murders—fares no better.
The Federal Death Penalty Act (FDPA) sets out a com-
prehensive scheme by which federal district courts adjudi-
cate, review, and impose death sentences. See 18 U. S. C.
§§3591 et seq. Section 3593 provides that, at the sentencing
phase of a capital trial, “information may be presented as
to any matter relevant to the sentence, including any miti-
gating or aggravating factor.” §3593(c). “Information is
admissible regardless of its admissibility under the rules
governing admission of evidence at criminal trials.” Ibid.
That said, FDPA proceedings are not evidentiary free-for-
alls. The district court may exclude information under the
FDPA “if its probative value is outweighed by the danger of
creating unfair prejudice, confusing the issues, or mislead-
ing the jury.” Ibid. We review these evidentiary exclusions
for abuse of discretion. See, e.g., United States v. Abel, 469
U. S. 45, 54 (1984); Sprint/United Management Co. v. Men-
delsohn, 552 U. S. 379, 384 (2008); 1 R. Mosteller et al.,
McCormick on Evidence §185, p. 1125 (8th ed. 2020).
Here, during sentencing, Dzhokhar sought to introduce
evidence linking Tamerlan to the unsolved Waltham mur-
ders. He argued that the evidence supported his mitigation
defense that Tamerlan was the ringleader. The District
Court acknowledged Dzhokhar’s rationale but excluded the
evidence because it was “without any probative value” and
“would be confusing to the jury.” App. 650. See 18 U. S. C.
§3593(c).
14 UNITED STATES v. TSARNAEV

Opinion of the Court

That conclusion was reasonable and not an abuse of the
District Court’s discretion. Dzhokhar sought to divert the
sentencing jury’s attention to a triple homicide that Tamer-
lan allegedly committed years prior, though there was no
allegation that Dzhokhar had any role in that crime. Nor
was there any way to confirm or verify the relevant facts,
since all of the parties involved were dead. As the District
Court explained, “there simply [was] insufficient evidence
to describe [any] participation Tamerlan may have had” or
“tel[l] who played what role, if they played roles.” App. 650.
The District Court did not abuse its discretion when finding
that the evidence lacked probative value, would confuse the
jury, and ultimately would be nothing more than “a waste
of time.” Ibid.
Dzhokhar and the dissent offer several counterargu-
ments, none of which is convincing. First, Dzhokhar sug-
gests that §3593(c) violates the Eighth Amendment if its
balancing test operates to exclude any relevant mitigating
evidence. See Brief for Respondent 17, 31; Tr. of Oral Arg.
85–88. His argument depends on a line of cases rooted in
Lockett v. Ohio, 438 U. S. 586 (1978), and Eddings v. Okla-
homa, 455 U. S. 104 (1982),2 which “requir[e] the sentencer
to consider mitigating circumstances when deciding
whether to impose the death penalty.” Jones v. Mississippi,
593 U. S. ___, ___ (2021) (slip op., at 17). Dzhokhar sug-
gests that a district court violates the Eighth Amendment
under these precedents if it excludes any marginally rele-
vant mitigating evidence that fails the §3593(c) balancing
test. See Tr. of Oral Arg. 85–88.
——————
2 Some have argued that these cases and their progeny do not reflect

the original meaning of the Eighth Amendment, whose prohibition “re-
lates to the character of the punishment, and not the process by which it
is imposed.” Gardner v. Florida, 430 U. S. 349, 371 (1977) (Rehnquist,
J., dissenting); see also, e.g., Miller v. Alabama, 567 U. S. 460, 505–506,
and n. 3 (2012) (THOMAS, J., dissenting). Neither party here asks us to
revisit that question and we decline to do so.
 Cite as: 595 U. S. ____ (2022) 15

Opinion of the Court

Our cases do not support Dzhokhar’s extreme position.
“ ‘Lockett and its progeny stand only for the proposition that
a State may not cut off in an absolute manner the presen-
tation of mitigating evidence, either by statute or judicial
instruction, or by limiting the inquiries to which it is rele-
vant so severely that the evidence could never be part of the
sentencing decision at all.’ ” Johnson v. Texas, 509 U. S.
350, 361 (1993) (quoting McKoy v. North Carolina, 494 U. S.
433, 456 (1990) (Kennedy, J., concurring in judgment)). We
read that principle to coexist with the overarching goal
“that, above all, capital sentencing must be reliable, accu-
rate, and nonarbitrary.” Saffle v. Parks, 494 U. S. 484, 493
(1990); accord, California v. Brown, 479 U. S. 538, 541
(1987). Thus, “[o]ur capital sentencing jurisprudence seeks
to reconcile [these] two competing . . . principles”—“to allow
mitigating evidence to be considered and to guide the dis-
cretion of the sentencer.” Johnson, 509 U. S., at 373. To
effectively reconcile these objectives, “[w]e need only con-
clude that it is consistent with the Eighth Amendment for
[the Federal Government] to channel the sentencer’s con-
sideration of a defendant’s arguably mitigating evidence so
as to limit the relevance of that evidence in any reasonable
manner, so long as the [Federal Government] does not deny
the defendant a full and fair opportunity to apprise the sen-
tencer of all constitutionally relevant circumstances.” Gra-
ham v. Collins, 506 U. S. 461, 498–499 (1993) (THOMAS, J.,
concurring).
Because the States and the Federal Government “retain
‘the traditional authority’ ” “to decide that certain types of
evidence may have insufficient probative value to justify
their admission,” they may enact reasonable rules govern-
ing whether specific pieces of evidence are admissible.
Skipper v. South Carolina, 476 U. S. 1, 11, 15 (1986) (Pow-
ell, J., concurring in judgment) (quoting Lockett, 438 U. S.,
at 604, n. 12). Moreover, we have expressly held that “the
16 UNITED STATES v. TSARNAEV

Opinion of the Court

Eighth Amendment does not deprive” a sovereign “of its au-
thority to set reasonable limits upon the evidence a [capital]
defendant can submit, and control the manner in which it
is submitted.” Oregon v. Guzek, 546 U. S. 517, 526 (2006).
Congress’ passage of §3593(c) falls well within that tradi-
tional authority. Section 3593(c) sets up a highly permis-
sive regime that allows criminal defendants to introduce a
wide range of normally inadmissible evidence. The statute
channels that evidence through an individualized balanc-
ing test that affords a capital defendant every reasonable
opportunity to place relevant mitigating evidence before the
penalty-phase jury. Unlike the statute challenged in Lock-
ett or the sentencer’s decision challenged in Eddings,
§3593(c) does not put any category of mitigating evidence
beyond the sentencer’s purview. Rather, §3593(c) preserves
the traditional gatekeeping function of district court judges
to consider and assess specific pieces of relevant evidence
in light of its probative value and the risks it poses to the
jury’s truth-seeking function. The court weighs all prof-
fered evidence to determine whether it will assist the jury
in considering any grounds for mitigation.
Put simply, §3593(c) “does not deny the defendant a full
and fair opportunity to apprise the sentencer of all consti-
tutionally relevant circumstances.” Graham, 506 U. S. at
498–499 (THOMAS, J., concurring). It therefore does not of-
fend the Eighth Amendment.
Dzhokhar alternatively disagrees with the balance that
the District Court struck here under §3593(c), arguing that
the Waltham evidence was “highly probative” to his mitiga-
tion defense. Brief for Respondent 17. On his telling, the
evidence showed that Tamerlan was a leader who pres-
sured others to commit violence. But the District Court con-
sidered that argument and rejected it after reasonably ex-
plaining that “[t]here’s just no way of telling who played
what role, if they played roles,” from the sparse and unreli-
able information before the court. App. 650. It was “as
 Cite as: 595 U. S. ____ (2022) 17

Opinion of the Court

plausible . . . that Todashev was the bad guy and Tamerlan
was the minor actor.” Ibid. In other words, the evidence
did not tend to show that Tamerlan acted as the leader who
pressured Todashev into committing the crime. And it cer-
tainly did not show that, almost two years later, Tamerlan
led and dominated Dzhokhar in a manner that would miti-
gate Dzhokhar’s guilt.
Dzhokhar further opines that he might have reduced ju-
ror confusion by putting the information before the jury in
a “streamlined” manner. Brief for Respondent 32. But “[i]t
is important that a reviewing court evaluate the trial
court’s decision from its perspective when it had to rule” ra-
ther than “indulge in review by hindsight.” Old Chief v.
United States, 519 U. S. 172, 182, n. 6 (1997). Here, Dzho-
khar did not alert the District Court to any possible
“streamlined” approach, instead suggesting that, if the
court admitted the Waltham evidence, he would submit ad-
ditional evidence and possibly seek third-party discovery.
Moreover, Dzhokhar could not have unilaterally dictated
how the proceeding would progress because the Govern-
ment would have been “permitted to rebut any information
received at the hearing” with evidence of its own. 18
U. S. C. §3593(c). So no matter how Dzhokhar presented
the evidence, its bare inclusion risked producing a confus-
ing mini-trial where the only witnesses who knew the truth
were dead. The District Court did not abuse its discretion
by declining to lead the jury into this evidentiary detour.
Finally, Dzhokhar argues that since the Government ap-
parently considered Todashev’s statement to the FBI
agents reliable enough to justify its reference in a search
warrant affidavit, Todashev’s statements were necessarily
reliable enough to be presented to the jury as mitigating
evidence. See Brief for Respondent 27–28; see also post, at
8 (BREYER, J., dissenting) (contending that the warrant
“strongly suggests” the District Court abused its discre-
tion). We fail to see why. The District Court here did not
18 UNITED STATES v. TSARNAEV

Opinion of the Court

sign the warrant or the affidavit. Whatever probable-cause
assessment the FBI agent and the Magistrate Judge made,
the District Court was free to evaluate the information in-
dependently when deciding whether to admit it under
§3593(c). As explained, that evaluation was not an abuse
of discretion.
For its part, the dissent subjects the District Court’s de-
cision to exclude the Waltham evidence to a more stringent
standard of review and, based on its independent review of
the record, would reverse. Post, at 5–16. While the dissent
acknowledges that district courts enjoy “significant discre-
tion” when making evidentiary decisions, post, at 5, it nev-
ertheless argues that the death penalty context here re-
quires us to scrutinize the District Court’s decision with
“particular judicial care,” post, at 15.
In doing so, the dissent ignores our traditional standard
for appellate review of evidentiary determinations.3 Defer-
ence is the “hallmark of [the] abuse-of-discretion review”
applicable to such decisions. General Elec. Co. v. Joiner,

——————
3 None of the dissent’s cases, see post, at 16, supports applying height-

ened scrutiny to evidentiary decisions in death-penalty cases. The lan-
guage the dissent cites from Kyles v. Whitley, 514 U. S. 419, 422 (1995),
about our “ ‘duty to search for constitutional error,’ ” post, at 14, in capital
cases is inapposite; it concerned our decision to grant review to engage
in fact-bound error correction, not the applicable standard for deciding
whether an error had in fact occurred. See 514 U. S., at 422, n. 1. Mean-
while, the language from Zant v. Stephens, 462 U. S. 862, 885 (1983),
about “careful scrutiny” concerned our review of the jury’s “deliberative
process” leading to the imposition of a capital sentence, not the consid-
ered evidentiary decisions of a District Court. Finally, Gregg v. Georgia,
428 U. S. 153, 187 (1976) (joint opinion of Stewart, Powell, Stevens, JJ.),
scrutinized whether procedural “safeguard[s]” were honored, not
whether the District Court’s evidentiary rulings were substantively rea-
sonable. All told, not one of these cases addressed, let alone altered, the
abuse-of-discretion standard traditionally applicable to a district court’s
evidentiary decisions. See General Elec. Co. v. Joiner, 522 U. S. 136, 141
(1997) (“We have held that abuse of discretion is the proper standard of
review of a district court’s evidentiary rulings”).
 Cite as: 595 U. S. ____ (2022) 19

Opinion of the Court

522 U. S. 136, 143 (1997). A “reviewing court” applying that
standard “must not substitute its judgment for that of the
district court.” Horne v. Flores, 557 U. S. 433, 493 (2009)
(BREYER, J., dissenting). Rather, an appellate court must
defer to the lower court’s “sound judgment,” so long as its
decision falls within its “wide discretion,” Abel, 469 U. S., at
54, and is not “ ‘manifestly erroneous,’ ” Joiner, 522 U. S., at
142 (quoting Spring Co. v. Edgar, 99 U. S. 645, 658 (1879)).
Even in the death penalty context, this traditional abuse-
of-discretion standard applies.
Yet here, the dissent proposes to independently reevalu-
ate the District Court’s decision to exclude the Waltham ev-
idence under §3593(c). In particular, the dissent joins
Dzhokhar in critiquing the District Court’s conclusion that
the risk of confusing the jury outweighed the probative
value of that evidence. See post, at 10–15. The dissent
thinks it was the “District Court’s strongest reason” for ex-
cluding the evidence, post, at 10, but it discounts the Dis-
trict Court’s conclusion for two reasons. Neither is compel-
ling, especially under the deferential abuse-of-discretion
standard.
First, the dissent suggests that because “death penalty
proceedings are special,” district courts should be more hes-
itant to find a risk of confusion in this context than in oth-
ers. Post, at 11. But the dissent identifies nothing in the
text of the FDPA to support its position. Congress defined
what considerations district courts must balance when
making admissibility determinations under §3593(c), and it
chose to define one using a term familiar in the law of evi-
dence—“confusing the issues.” Compare §3593(c) with Fed-
eral Rule of Evidence 403; see also Mosteller, McCormick
on Evidence §185, at 1119 (noting “common law power of
the judge to exclude relevant evidence” to forestall “ ‘confu-
sion of the issues’ ”). Nothing suggests that Congress in-
tended district courts to evaluate that concern differently
under the FDPA.
20 UNITED STATES v. TSARNAEV

Opinion of the Court

Second, the dissent points out that district courts some-
times allow the Government to present evidence of a capital
defendant’s past bad acts during sentencing proceedings,
despite the risk of evidentiary minitrials. See post, at 13–
15. But many of those cases focused on the defendant’s own
conduct, not someone else’s. See ibid. In such cases, the
Government need only put on evidence tending to show that
the defendant committed the past bad act. See, e.g., United
States v. Umaña, 750 F. 3d 320, 348–349 (CA4 2014). Here,
the evidentiary showing would be substantially more com-
plex and confusing. No one alleges that Dzhokhar partici-
pated in the Waltham murders, and, as the District Court
reasonably concluded, the evidence available sheds little
light on what role (if any) Tamerlan actually played. See
App. 650. To make his point at sentencing, then, Dzhokhar
would first have to show, without any surviving witnesses,
what role Tamerlan actually played. Then, he would have
to establish that he learned of the Waltham crimes before
planning the bombings. Finally, he would have to explain
how his knowledge of Tamerlan’s role in a nearly 2-year-old
violent robbery affected his own role in the bombings.
Whatever other courts might think about an inquiry into a
defendant’s own prior bad acts, this District Court reason-
ably thought that the Waltham murder inquiry risked con-
fusing the jury in these proceedings. We see no basis to
disturb that conclusion.
III
Dzhokhar Tsarnaev committed heinous crimes. The
Sixth Amendment nonetheless guaranteed him a fair trial
before an impartial jury. He received one. The judgment
of the United States Court of Appeals for the First Circuit
is reversed.
It is so ordered.
 Cite as: 595 U. S. ____ (2022) 1

B ARRETT, J., concurring

SUPREME COURT OF THE UNITED STATES
_________________

No. 20–443
_________________

UNITED STATES, PETITIONER v.
DZHOKHAR A. TSARNAEV
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE FIRST CIRCUIT
[March 4, 2022]

JUSTICE BARRETT, with whom JUSTICE GORSUCH joins,
concurring.
In this case, the First Circuit asserted “supervisory
power” to impose a procedural rule on the District Court.
Because that rule (which required a district court to ask
media-content questions on request in high-profile prosecu-
tions) conflicts with our cases (which hold that a district
court has broad discretion to manage jury selection), I agree
with the Court that the First Circuit erred.
I write separately to note my skepticism that the courts
of appeals possess such supervisory power in the first place.
Article III’s grant of “[t]he judicial Power” imbues each fed-
eral court with the inherent authority to regulate its own
proceedings. U. S. Const., Art. III, §1; Chambers v.
NASCO, Inc., 501 U. S. 32, 43 (1991) (“It has long been un-
derstood that ‘[c]ertain implied powers must necessarily re-
sult to our Courts of justice from the nature of their institu-
tion,’ powers ‘which cannot be dispensed with in a Court,
because they are necessary to the exercise of all others’ ”
(quoting United States v. Hudson, 7 Cranch 32, 34 (1812))).
This authority permits federal courts to handle a range of
matters, big and small, that fall in the gaps of governing
statutes and formally adopted procedural rules. See, e.g.,
Link v. Wabash R. Co., 370 U. S. 626 (1962) (a district court
can dismiss a case sua sponte for failure to prosecute);
2 UNITED STATES v. TSARNAEV

B ARRETT, J., concurring

Hazel-Atlas Glass Co. v. Hartford-Empire Co., 322 U. S. 238
(1944) (a court of appeals can vacate its judgment upon dis-
covering fraud). But here, the First Circuit did not adopt a
rule regulating its own proceedings—it adopted a blanket
rule that all district courts in its jurisdiction must follow on
pain of reversal.
In fairness to the First Circuit, we have suggested that
the courts of appeals possess authority to dictate procedural
rules for district courts. See, e.g., Cuyler v. Sullivan, 446
U. S. 335, 346, n. 10 (1980) (citing Courts of Appeals deci-
sions requiring district courts to inquire into potential con-
flicts of interest and referring to this as “a desirable prac-
tice”); Cupp v. Naughten, 414 U. S. 141, 146 (1973)
(suggesting in dicta that a court of appeals may require a
district court “to follow procedures deemed desirable from
the viewpoint of sound judicial practice although in nowise
commanded by statute or by the Constitution”).* Under-
standably, then, the First Circuit followed our lead. But
before we go further down this road, we should reexamine
the map. Not only have we failed to identify a source for
——————
*In dissent, JUSTICE BREYER asserts that “our precedents clearly rec-
ognize the existence of ” the courts of appeals’ supervisory power. Post,
at 17. But the cases cited by J USTICE BREYER reflect our sometimes im-
precise use of the term “supervisory power.” Rather than using the term
to refer to a court of appeals’ authority to impose procedures on an infe-
rior court, two of the cited cases use it to refer to a court’s power to “su-
pervise” its own proceedings. See Ortega-Rodriguez v. United States, 507
U. S. 234, 249–250 (1993) (addressing a court of appeals’ ability to dis-
miss an appeal of a former fugitive); Thomas v. Arn, 474 U. S. 140, 142
(1985) (a court of appeals may “establish a rule that the failure to file
objections to the magistrate’s report waives the right to appeal the dis-
trict court’s judgment”). And in the third case, United States v. Hasting,
461 U. S. 499 (1983), the Court operated on the assumption that the
Court of Appeals had exercised “its supervisory powers to discipline the
prosecutors of its jurisdiction,” not to regulate district courts. Id., at 505
(emphasis added). The bottom line is that these cases do not address,
much less endorse, the kind of supervisory authority that the First Cir-
cuit asserted here.
 Cite as: 595 U. S. ____ (2022) 3

B ARRETT, J., concurring

this supposed authority, it is unclear that any exists.
To be sure, this Court has squarely asserted supervisory
power to regulate procedure in lower federal courts. See
McNabb v. United States, 318 U. S. 332 (1943). While we
have not justified this power either, it has an at least argu-
able basis: the Constitution’s establishment of this Court as
“supreme,” as distinct from the “inferior Courts” that Con-
gress has discretion to create. Art. III, §1. Much like the
grant of “[t]he judicial Power” carries with it inherent au-
thority over local procedure, this Court’s designation as “su-
preme” might carry with it some inherent authority to pre-
scribe procedural rules for inferior federal courts. But see
ante, at 11, n. 1. In the end, this argument might be unsup-
ported by the Constitution’s structure and history. Still,
the text of Article III makes it plausible.
Yet whatever the status of this Court’s supervisory au-
thority, it is difficult, if not impossible, to find any compa-
rable constitutional hook for such power in the courts of ap-
peals. Nor does any statute grant them this general
authority. And while it is tempting to roll supervisory au-
thority into the power of appellate review, the two are ana-
lytically distinct. A court engaged in appellate review in
this context determines whether a lower court exceeded its
inherent authority to make a procedural choice. A court as-
serting supervisory authority imposes its own procedural
choice on the lower court. In other words, supervisory au-
thority is not necessarily a lesser included power of appel-
late review.
This case does not require us to resolve whether the
courts of appeals have supervisory authority over district
courts. Either way, the First Circuit erred. At some point
in the future, however, it would be worth revisiting our
dicta.
 Cite as: 595 U. S. ____ (2022) 1

BREYER, J., dissenting

SUPREME COURT OF THE UNITED STATES
_________________

No. 20–443
_________________

UNITED STATES, PETITIONER v.
DZHOKHAR A. TSARNAEV
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE FIRST CIRCUIT
[March 4, 2022]

JUSTICE BREYER, with whom JUSTICE SOTOMAYOR and
JUSTICE KAGAN join except as to Part II–C, dissenting.
During the sentencing phase of his murder trial, Boston
Marathon bomber Dzhokhar Tsarnaev argued that he
should not receive the death penalty primarily on the
ground that his older brother Tamerlan took the leading
role and induced Dzhokhar’s participation in the bombings.
Dzhokhar argued that Tamerlan was a highly violent man,
that Tamerlan radicalized him, and that Dzhokhar partici-
pated in the bombings because of Tamerlan’s violent influ-
ence and leadership. In support of this argument, Dzho-
khar sought to introduce evidence that Tamerlan
previously committed three brutal, ideologically inspired
murders in Waltham, Massachusetts. The District Court
prohibited Dzhokhar from introducing this evidence. The
Court of Appeals held that the District Court abused its dis-
cretion by doing so. 968 F. 3d 24, 73 (CA1 2020).
This Court now reverses the Court of Appeals. In my
view, the Court of Appeals acted lawfully in holding that
the District Court should have allowed Dzhokhar to intro-
duce this evidence. See Lockett v. Ohio, 438 U. S. 586, 604
(1978) (plurality opinion) (criminal defendant charged with
capital crime has constitutional right to present “any aspect
of [his] character or record and any of the circumstances of
2 UNITED STATES v. TSARNAEV

BREYER, J., dissenting

the offense that the defendant proffers as a basis for a sen-
tence less than death”); Eddings v. Oklahoma, 455 U. S.
104, 110 (1982) (adopting Lockett’s plurality rule). Conse-
quently, I dissent.
I
During the guilt phase of Dzhokhar’s trial, Dzhokhar
acknowledged that he participated in the Boston Marathon
bombings. He conceded that he and his older brother Tam-
erlan planted bombs along the route of the Patriot’s Day
Marathon and that the bombs killed or injured many inno-
cent people. Given Dzhokhar’s concession, his trial focused
almost exclusively on sentencing, in particular whether
Dzhokhar should receive the death penalty. Dzhokhar ar-
gued in mitigation that his conduct was less serious than
Tamerlan’s and that Tamerlan’s radicalizing influence was
a major reason that Dzhokhar participated in the bomb-
ings. See Sears v. Upton, 561 U. S. 945, 950 (2010) (per cu-
riam) (older brother’s criminal record and introduction of
defendant “to a life of crime” supported mitigation theory
that defendant “may have desired to follow in the footsteps”
of his older brother); Lockett, 438 U. S., at 608 (“defendant’s
comparatively minor role in the offense” is relevant mitigat-
ing factor).
In support of this theory, the District Court allowed
Dzhokhar to argue that: (1) Dzhokhar “acted under the in-
fluence of his older brother” Tamerlan; (2) Dzhokhar “would
not have committed the crimes but for [his] older brother
Tamerlan”; (3) Dzhokhar “was particularly susceptible to
his older brother’s influence,” “[w]hether because of Tamer-
lan’s age, size, aggressiveness, domineering personality,
privileged status in the family, traditional authority as the
eldest brother, or other reasons”; (4) Tamerlan “planned,
led, and directed the Marathon bombing”; and (5) Tamerlan
“became radicalized first, and then encouraged his younger
brother to follow him.” App. 614, 616 (boldface omitted).
 Cite as: 595 U. S. ____ (2022) 3

BREYER, J., dissenting

The District Court also allowed Dzhokhar to introduce cer-
tain evidence in support of this mitigation theory. This in-
cluded evidence that Tamerlan had behaved aggressively in
the past, and that Dzhokhar looked up to Tamerlan. But
the court did not allow Dzhokhar to introduce evidence of
Tamerlan’s participation in the Waltham murders.
The “Waltham murders” refers to the killing of three drug
dealers in Waltham, Massachusetts. The murders took
place on September 11, 2011, the 10th anniversary of the
9/11 terrorist attacks, and about a year and a half before
the Boston Marathon bombings. The evidence relating to
the Waltham murders came primarily from FBI agent in-
terviews of Ibragim Todashev, a friend of Tamerlan’s. Dur-
ing the FBI interviews, Todashev (who attacked the agents
and was killed midinterview) initially denied participating
in the murders but later said that he and Tamerlan had
committed them.
In particular, Todashev said that it was Tamerlan’s idea
to rob the drug dealers, one of whom was Tamerlan’s close
friend. Todashev said that they both went to the drug deal-
ers’ house, threatened the drug dealers at gun point, bound
them with duct tape, and searched the house for money.
Tamerlan then beat up the dealers and, in an attempt to
get more money, threatened to stab them. Todashev also
said that Tamerlan insisted on killing the drug dealers
(even though Todashev “ ‘begged him not to’ ”), and that
Todashev, feeling like he had no “way out,” waited outside
the house while Tamerlan slit their throats. Id., at 915,
948. Finally, Todashev said that Tamerlan called him back
inside to help clean up after the drug dealers were dead and
that the two left with about $40,000 of stolen money.
The FBI relied on Todashev’s statements to obtain a
search warrant for Tamerlan’s car, which agents believed
was the car used to drive to and from the drug dealers’
house. An FBI affidavit attached to the search warrant re-
quest stated that Todashev had
4 UNITED STATES v. TSARNAEV

BREYER, J., dissenting

“confessed that he and Tamerlan participated in the
Waltham murders. He said that he and Tamerlan had
agreed initially just to rob the victims, whom they
knew to be drug dealers . . . . Todashev said that Tam-
erlan had a gun, which he brandished to enter the res-
idence. Tamerlan decided that they should eliminate
any witnesses to the crime, and then Todashev and
Tamerlan bound the victims, who were ultimately mur-
dered.” Id., at 998.
Based on this and other less significant evidence, the FBI
agent asserted that there was “probable cause to believe
that Todashev and Tamerlan planned and carried out” the
Waltham Murders. Id., at 996. A federal judge agreed, and
issued a warrant.
Other evidence uncovered during the FBI’s investigation
of the Boston Marathon bombings also related to the Wal-
tham murders. Dias Kadyrbayev, a friend of Dzhokhar’s,
stated that a few months before the bombings Dzhokhar
learned of Tamerlan’s involvement in the Waltham mur-
ders. Kadyrbayev said that Dzhokhar described Tamer-
lan’s participation in the murders as “ ‘commit[ting] jihad.’ ”
Id., at 584. Investigators also found al Qaeda propaganda
on Tamerlan’s computer that advocated stealing money
from non-Muslims as a way to support jihadist principles.
Dzhokhar was prohibited from introducing any of this ev-
idence during the sentencing phase of his trial. At the end
of his sentencing proceeding, and without hearing any evi-
dence about the Waltham murders, eight jurors found that
Tamerlan had become radicalized before Dzhokhar and en-
couraged Dzhokhar to follow his example. Id., at 616.
Three found that Tamerlan planned, led, and directed the
bombings. Id., at 614. Three also found that Dzhokhar
acted under Tamerlan’s influence, that he was particularly
susceptible to Tamerlan’s influence, and that he would not
have committed the bombings but for Tamerlan. Ibid. The
 Cite as: 595 U. S. ____ (2022) 5

BREYER, J., dissenting

jury nonetheless unanimously recommended the death pen-
alty for Dzhokhar in respect to those counts involving the
bomb that he himself—and he alone—had placed. The Dis-
trict Court then sentenced Dzhokhar to death.
Dzhokhar appealed. As the Court explains, the Court of
Appeals held that the District Court had to conduct a new
sentencing proceeding for two independent reasons. Ante,
at 7. First, the trial court had not adequately questioned
potential jury members about the content of the pretrial
publicity they had seen. Second, the trial court did not per-
mit Dzhokhar to introduce evidence about the Waltham
murders during the sentencing phase of his trial. I disagree
with the Court’s decision (and I agree with the Court of Ap-
peals) at least as to the second reason.
II
A
The Federal Death Penalty Act sets forth the legal stand-
ards governing the admissibility of mitigating evidence dur-
ing a capital sentencing. See 18 U. S. C. §3591 et seq. The
statute provides an admissibility standard unique to death
penalty cases. It says that in death penalty sentencing pro-
ceedings, “information may be presented as to any matter
relevant to the sentence, including any mitigating or aggra-
vating factor.” §3593(c). And that is so whether that “in-
formation” is or is not admissible “under the rules govern-
ing admission of evidence at criminal trials.” Ibid. The
statute also provides that a trial court “may” exclude evi-
dence “if its probative value is outweighed by the danger of
creating unfair prejudice, confusing the issues, or mislead-
ing the jury.” Ibid.
As the majority points out, district courts have significant
discretion in deciding how to apply and weigh the statute’s
factors. Ante, at 13–14. But “abuse-of-discretion review is
not toothless; and it is entirely proper for a reviewing court
6 UNITED STATES v. TSARNAEV

BREYER, J., dissenting

to find an abuse of discretion when important fac-
tors . . . are ‘slighted.’ ” Gall v. United States, 552 U. S. 38,
72 (2007) (ALITO, J., dissenting) (quoting United States v.
Taylor, 487 U. S. 326, 337 (1988)); see also American Paper
Institute, Inc. v. American Elec. Power Service Corp., 461
U. S. 402, 413 (1983) (to decide whether action was abuse
of discretion, “we must determine whether the [court] ade-
quately considered the factors relevant” to the question);
Highmark Inc. v. Allcare Health Management System, Inc.,
572 U. S. 559, 564, n. 2 (2014) (“The abuse-of-discretion
standard does not preclude an appellate court’s correction
of a district court’s . . . clearly erroneous assessment of the
evidence” (internal quotation marks omitted)). And here,
we review for abuse of discretion in the context of “a matter
so grave as the determination of whether a human life
should be taken or spared.” Gregg v. Georgia, 428 U. S. 153,
189 (1976) (joint opinion of Stewart, Powell, and Stevens,
JJ.). I therefore apply the standard with care. Cf. id., at
187 (“When a defendant’s life is at stake, the Court has been
particularly sensitive to insure that every safeguard is ob-
served”); Zant v. Stephens, 462 U. S. 862, 885 (1983) (“[T]he
severity of the [capital] sentence mandates careful scrutiny
in the review of any colorable claim of error”).
The District Court here excluded the Waltham evidence
for the following four reasons:
“[T]here simply is [1] insufficient evidence to describe
what participation Tamerlan may have had in those
events. . . . From my review of the evidence, . . . it is as
plausible, which is not very, that Todashev was the bad
guy and Tamerlan was the minor actor. There’s just no
way of telling who played what role, if they played
roles. So it simply would be [2] confusing to the jury
and [3] a waste of time, I think, without very—[4] with-
out any probative value.” App. 650.
I have reviewed the record keeping in mind the reasons the
 Cite as: 595 U. S. ____ (2022) 7

BREYER, J., dissenting

District Court gave: (1) no probative value; (2) insufficient
evidence to corroborate Tamerlan’s role in the murders;
(3) waste of time; and (4) jury confusion. Reading the rec-
ord in light of these factors, I believe that the Court of Ap-
peals was correct that the District Court abused its discre-
tion by excluding the Waltham evidence. The record does
not adequately support exclusion for the District Court’s
stated reasons.
Consider the factors that the District Court directly and
indirectly took into account.
1. Relevance/Probative Value
The District Court was wrong when it described the Wal-
tham evidence as lacking “any probative value.” The evi-
dence met the “threshold for relevance” applicable here.
Tennard v. Dretke, 542 U. S. 274, 285 (2004); id., at 284
(“Relevant mitigating evidence is evidence which tends log-
ically to prove or disprove some fact or circumstance which
a fact-finder could reasonably deem to have mitigating
value” (internal quotation marks omitted)). And it pos-
sessed probative value.
The Waltham evidence tended to show that Tamerlan
was involved in a brutal triple murder, possibly over
Todashev’s objections, a year and a half before the bomb-
ings. The evidence tended to show that Tamerlan commit-
ted these murders for ideological reasons. This is true
(though to a lesser degree) even if Tamerlan played a sec-
ondary, rather than the primary, role in the Waltham kill-
ings. Evidence that Tamerlan participated in (and poten-
tially orchestrated) one set of ideologically motivated
murders in 2011 supports the claim that Tamerlan was the
violent, radicalizing force behind the ideologically moti-
vated bombings a year and a half later.
2. Corroboration/Reliability
The Waltham evidence was corroborated and sufficiently
8 UNITED STATES v. TSARNAEV

BREYER, J., dissenting

reliable to warrant presentation to the jury. Dzhokhar’s
friend Kadyrbayev said that Dzhokhar believed Tamerlan
was involved in the Waltham killings. Kadyrbayev also
said that Dzhokhar told him that Tamerlan “had committed
jihad” in Waltham. Relatedly, Tamerlan had al Qaeda
propaganda on his computer that advocated stealing money
from non-Muslims as a way to support jihadist principles.
There was also evidence that a week or so after the Wal-
tham killings, someone ran internet searches on Tamer-
lan’s wife’s computer for “3 men killed in Waltham,” “men
kill in Waltham,” and “tamerlan tsarnaev.” App. 590. Tam-
erlan’s wife also confirmed that Tamerlan was close friends
with one of the drug dealers, and there was evidence that
Tamerlan did not attend that friend’s funeral, which some
thought strange given their close relationship.
Further, the Waltham evidence was sufficiently reliable
for the Government to conclude (via FBI affidavit) that it
helped to establish probable cause that Tamerlan commit-
ted the Waltham murders. It was reliable enough for a fed-
eral judge to issue a search warrant for Tamerlan’s car to
look for evidence of those murders. It is of course true, as
the majority points out, that the District Court was free to
make an independent assessment of the reliability of the
evidence. Ante, at 17–18. But the fact that both the Gov-
ernment and a federal judge found the evidence sufficiently
reliable to establish probable cause that Tamerlan commit-
ted the murders strongly suggests that the District Court
here abused its discretion in concluding that the same evi-
dence was so unreliable that Dzhokhar could not use it as
mitigating evidence to establish the same proposition. Cf.
Florida v. Harris, 568 U. S. 237, 243 (2013) (probable cause
exists when facts “would warrant a person of reasonable
caution in the belief that contraband or evidence of a crime
is present” (internal quotation marks and brackets omitted;
emphasis added)).
 Cite as: 595 U. S. ____ (2022) 9

BREYER, J., dissenting

3. Waste of Time/Need
The Waltham evidence was not simply cumulative of
other mitigation evidence. And it was critically important
to Dzhokhar’s mitigation defense. Apart from the Waltham
evidence, the evidence of Tamerlan’s aggressive nature and
violent tendencies consisted of evidence showing (1) that
Tamerlan physically abused his then-girlfriend (later wife);
(2) that he twice became disruptive and shouted at an Imam
during prayers; (3) that he poked someone in the chest dur-
ing an argument; (4) that he punched a man in the street
after the man said something Tamerlan did not like;
(5) that Tamerlan yelled at a local butcher who was selling
halal turkey for Thanksgiving; and (6) that Tamerlan was
disruptive at his boxing gym. Participation in a robbery
and triple murder is much stronger evidence of Tamerlan’s
violent nature than any of these incidents. Cf. Skipper v.
South Carolina, 476 U. S. 1, 8 (1986) (reversible error
where excluded mitigating evidence had “greater weight”
than evidence supporting same mitigating factors).
Similarly, the evidence introduced to show Tamerlan’s in-
fluence over Dzhokhar consisted of evidence showing (1)
their age difference (Tamerlan was 26 at the time of the
bombings, Dzhokhar 19); (2) the fact that Dzhokhar looked
up to and followed his older brother; (3) that in the brothers’
Chechen culture, Tamerlan, as the older sibling, held a po-
sition of authority and superiority vis-à-vis Dzhokhar; (4)
that Tamerlan sent Dzhokhar articles containing extremist
propaganda; and (5) that Tamerlan traveled to Russia in
2012 as part of an unsuccessful effort to wage “jihad.” But
the Waltham evidence showed (if the jury believed
Todashev’s account) that Tamerlan had previously exerted
such influence over Todashev as to make him an unwilling
accomplice to a triple murder. This is much stronger evi-
dence of Tamerlan’s capacity to influence than any evidence
that the jury heard.
10 UNITED STATES v. TSARNAEV

BREYER, J., dissenting

Moreover, Dzhokhar had particular need for the Wal-
tham evidence in the context of his sentencing. As both
counsel emphasized during closing argument, the critical
mitigation issue was the two brothers’ comparative respon-
sibility. Dzhokhar’s counsel argued, for example, that “if
not for Tamerlan, this wouldn’t have happened. Dzhokhar
would never have done this but for Tamerlan.” App. 839–
840. The prosecution similarly told the jury that “the bulk
of [Dzhokhar’s] mitigation case comes down to a single
proposition: ‘His brother made him do it.’ ” Id., at 857. The
prosecution also told the jury that it should reject this prop-
osition because Dzhokhar’s mitigation evidence merely
showed that Tamerlan was “loud,” “bossy,” and “sometimes
lost his temper.” Id., at 861, 864. Would the prosecution
have made the same argument had the evidence required it
to add, “and perhaps slit the throats of three people”? Cf.
Clemons v. Mississippi, 494 U. S. 738, 753 (1990) (errone-
ous jury instruction reversible error where “repeatedly em-
phasized and argued” by prosecution); Skipper, 476 U. S.,
at 5, n. 1 (exclusion of evidence reversible error when evi-
dence related to issue “underscored . . . by the prosecutor’s
closing argument”).
The prosecution went on to argue that Tamerlan and
Dzhokhar were “equals,” and that it was only once Dzho-
khar “made the decision to become a terrorist, that Tamer-
lan was able to go into action.” App. 873–874. Would the
prosecution have made that same claim in the face of evi-
dence that Tamerlan had taken “action” a year and a half
before the bombings, on the anniversary of 9/11, and that
Dzhokhar characterized this action as “jihad”? The ex-
cluded evidence went to the heart of these critical sentenc-
ing issues.
4. Jury Confusion
In my view, the District Court’s strongest reason for ex-
 Cite as: 595 U. S. ____ (2022) 11

BREYER, J., dissenting

cluding the Waltham evidence, and the majority’s best ar-
gument for reversing the Court of Appeals, is that admit-
ting the evidence might have confused the jurors by
prompting a “minitrial” about what actually happened in
Waltham and what role Tamerlan played. The Federal
Death Penalty Act says that a court “may” exclude relevant
evidence “if its probative value is outweighed by the danger
of . . . confusing the issues, or misleading the jury.”
§3593(c). Given the trial judge’s discretionary authority to
admit or exclude evidence, could the possibility of juror con-
fusion overcome the pro-admission factors I have so far dis-
cussed? Two reasons convince me that it could not, and
that, concerns about jury confusion notwithstanding, the
District Court abused its discretion by excluding the evi-
dence.
First, death penalty proceedings are special. Unlike evi-
dentiary determinations made in other contexts, a trial
court’s decision to admit or exclude evidence during a capi-
tal sentencing proceeding is made against the backdrop of
a capital defendant’s constitutional right to argue against
the death penalty. See Tennard, 542 U. S., at 285 (“[T]he
Eighth Amendment requires that the jury be able to con-
sider and give effect to a capital defendant’s mitigating ev-
idence” (internal quotation marks omitted)). So, although
the Federal Death Penalty Act incorporates some of the fea-
tures that ordinarily guide a trial judge’s discretionary de-
cision to admit or exclude evidence, see Fed. Rule Evid. 403,
it also provides a special admissibility standard unique to
the capital sentencing context. Specifically, the statute
says that “information may be presented as to any matter
relevant to the sentence, including any mitigating or aggra-
vating factor,” regardless of whether that information
would be admissible under normal evidentiary rules.
§3593(c) (emphasis added). The statute thus tips the bal-
ance in favor of admitting mitigating evidence, even if ad-
12 UNITED STATES v. TSARNAEV

BREYER, J., dissenting

mission means increasing the length of a proceeding by in-
viting some “minitrials” over subsidiary issues. Cf. McKoy
v. North Carolina, 494 U. S. 433, 442 (1990) (“The Consti-
tution requires States to allow consideration of mitigating
evidence in capital cases”); see also Smith v. Texas, 543
U. S. 37, 44 (2004) (per curiam). This weighted scale makes
sense in the context of capital proceedings, in a way it would
not make sense in run-of-the-mill evidentiary disputes,
“[g]iven that the imposition of death . . . is so profoundly
different from all other penalties.” Lockett, 438 U. S., at 605
(plurality opinion). Indeed, because “the penalty of death
is qualitatively different from” all other punishments,
“there is a corresponding difference in the need for reliabil-
ity in the determination that death is the appropriate pun-
ishment in a specific case.” Woodson v. North Carolina, 428
U. S. 280, 305 (1976) (plurality opinion). And a jury’s deci-
sion to impose the death penalty is more reliable if it is
made after considering relevant mitigation evidence that
counsels against imposing such a sentence. See Lockett,
438 U. S., at 605 (emphasizing the need in capital cases to
give “independent mitigating weight to aspects of
the . . . circumstances of the offense proffered in mitiga-
tion”).
At the same time, a trial judge normally can control the
presentation of evidence to avoid unwarranted detours and
to ensure a trial does not extend beyond reasonable limits.
See, e.g., Fed. Rule Evid. 105 (court can instruct jury that it
may consider evidence for one purpose but not another);
Geders v. United States, 425 U. S. 80, 86–87 (1976) (“Within
limits, the judge . . . may refuse to allow cumulative, repet-
itive, or irrelevant testimony, and may control the scope of
examination of witnesses” (citations omitted)). In the con-
text of capital sentencing, then, concerns about juror “waste
of time” or the risk of “confusion” are less justifiable bases
on which to exclude an entire category of evidence that may
have significant mitigating value.
 Cite as: 595 U. S. ____ (2022) 13

BREYER, J., dissenting

Second, and perhaps of greater importance, a sampling of
other death penalty proceedings indicates that the prosecu-
tion often introduces evidence of a defendant’s prior crimi-
nal behavior in support of the death penalty, including evi-
dence that poses a similar risk of jury confusion. Trial
judges admit this evidence under the same admissibility
standard that governs the admission of mitigating evi-
dence. See §3593(c) (governing admissibility of evidence
supporting “aggravating,” as well as “mitigating,” factors).
And trial courts admit this evidence not because the defend-
ant’s past criminal behavior is directly relevant to the crime
at issue but because it supports an “aggravating” death-
penalty-related factor such as a defendant’s risk of future
dangerousness. If courts admit evidence of past criminal
behavior, unrelated to the crime at issue, to show aggravat-
ing circumstances, why should they not do the same to show
mitigating circumstances?
Moreover, capital sentencing courts routinely admit this
kind of evidence even if the past criminal behavior did not
result in formal charges or convictions (and thus has not
been proved to a jury or judge). See, e.g., United States v.
Gabrion, 719 F. 3d 511, 518 (CA6 2013) (District Court ad-
mitted evidence of defendant’s “likely role in the disappear-
ance (and presumably murder) of three other people”);
United States v. Runyon, 707 F. 3d 475, 504–505 (CA4
2013) (District Court did not abuse its discretion in admit-
ting evidence of defendant’s assault charges that were later
dismissed); United States v. Snarr, 704 F. 3d 368, 395 (CA5
2013) (District Court admitted evidence that defendant
“participated in a drive-by shooting and allegedly murdered
a man”); United States v. Lighty, 616 F. 3d 321, 341 (CA4
2010) (District Court admitted evidence that defendant was
involved in driveby shooting for which he was never
charged); United States v. Brown, 441 F. 3d 1330, 1368
(CA11 2006) (District Court admitted evidence that “de-
fendant has committed an array of other criminal acts,
14 UNITED STATES v. TSARNAEV

BREYER, J., dissenting

some but not all of which have resulted in conviction”).
Further, trial courts admit this evidence despite claims
that the evidence is not reliable (thus risking “minitrials”).
See, e.g., United States v. Coonce, 932 F. 3d 623, 641 (CA8
2019); United States v. Umaña, 750 F. 3d 320, 348–349
(CA4 2014); United States v. Hager, 721 F. 3d 167, 201 (CA4
2013); United States v. Higgs, 353 F. 3d 281, 323 (CA4
2003).
The evidentiary showing Dzhokhar attempted to make
here was not, as the majority asserts, any more complex or
confusing than the evidentiary showing the Government
makes in these situations. Cf. ante, at 20. To the contrary,
just as the Government introduces evidence of a defend-
ant’s prior unproved bad conduct to show a defendant’s dan-
gerousness, so too did Dzhokhar seek to introduce evidence
of Tamerlan’s prior unproved bad conduct to show Tamer-
lan’s dangerousness. The fact that the evidence was about
Tamerlan’s character instead of Dzhokhar’s did not render
the evidence beyond the jury’s ability to comprehend. The
District Court implicitly recognized as much when it al-
lowed Dzhokhar to introduce other evidence of Tamerlan’s
past conduct—conduct in which Dzhokhar did not partici-
pate.
Indeed, this Court has rejected concerns that distracting
minitrials should preclude the Government from introduc-
ing evidence about a nondefendant third party to show ag-
gravation. See Payne v. Tennessee, 501 U. S. 808, 823
(1991) (rejecting reasoning that victim impact evidence
should be excluded from sentencing proceeding because it
would “creat[e] a mini-trial on the victim’s character” (in-
ternal quotation marks omitted)). Why then should the
same concern preclude a defendant from introducing simi-
lar evidence in mitigation? After all, the Government, un-
like a defendant, has no constitutional right to present evi-
dence during a capital sentencing proceeding. Cf. Tennard,
542 U. S., at 285 (“[T]he Eighth Amendment requires that
 Cite as: 595 U. S. ____ (2022) 15

BREYER, J., dissenting

the jury be able to consider and give effect to a capital de-
fendant’s mitigating evidence” (internal quotation marks
omitted)).
I conclude, then, that the reasons the District Court gave
do not justify excluding the Waltham murder evidence, and
it was an abuse of discretion to do so. Nor was the exclusion
harmless. See §3595(c)(2)(C) (death sentence can be va-
cated if Government fails to prove beyond a reasonable
doubt that an error was harmless). Dzhokhar conceded his
guilt. The only issue was whether he deserved to die. Tell-
ingly, the jury’s nuanced verdict reflected close attention to
the relationship between the brothers: The jury did not rec-
ommend the death penalty for the charges related to the
actions Dzhokhar took together with Tamerlan, and only
recommended death for the charges related to the actions
Dzhokhar took alone. The Waltham evidence supported
Dzhokhar’s theory that Tamerlan’s violent and radicalizing
influence induced all of the actions Dzhokhar took in con-
nection with the Boston Marathon bombings. This evidence
may have led some jurors to conclude that Tamerlan’s in-
fluence was so pervasive that Dzhokhar did not deserve to
die for any of the actions he took in connection with the
bombings, even those taken outside of Tamerlan’s presence.
And it would have taken only one juror’s change of mind to
have produced a sentence other than death, even if a severe
one. See §3593(e) (death verdict must be unanimous).
B
Three courts including this Court have now examined
this record with care. Why? Why are appellate courts so
deeply involved in what is, after all, a trial-based eviden-
tiary matter? The reason, in my view, lies in part in the
nature of the underlying proceeding. It is a death penalty
proceeding. And where death is at stake, the courts (and
Congress) believe that particular judicial care is required.
See §3593 (detailing unique procedures applicable to the
16 UNITED STATES v. TSARNAEV

BREYER, J., dissenting

“[s]pecial hearing to determine whether a sentence of death
is justified” (boldface omitted)); Cf. Kyles v. Whitley, 514
U. S. 419, 422 (1995) (“[O]ur duty to search for constitu-
tional error with painstaking care is never more exacting
than it is in a capital case” (internal quotation marks omit-
ted)); Zant, 462 U. S., at 885 (“[T]he severity of the [death]
sentence mandates careful scrutiny in the review of any col-
orable claim of error”); Gregg, 428 U. S., at 187 (joint opin-
ion) (“When a defendant’s life is at stake, the Court has
been particularly sensitive to insure that every safeguard
is observed”); Glossip v. Gross, 576 U. S. 863, 937 (2015)
(BREYER, J., dissenting) (“[I]t is difficult for judges, as it
would be difficult for anyone, not to apply legal require-
ments punctiliously when the consequences of failing to do
so may well be death”). That same care applies on abuse-
of-discretion review, just as it does for any other standard.
The extra time that close examination takes is part of the
procedural price that a judicial system allowing the death
penalty will inevitably exact.
C
I have written elsewhere about the problems inherent in
a system that allows for the imposition of the death penalty.
See, e.g., id., at 909–938. This case provides just one more
example of some of those problems.
III
In my view, the Court of Appeals was correct in its Wal-
tham evidence conclusion. For that reason, the District
Court should conduct a new sentencing proceeding. I need
not, and do not, reach the pretrial publicity question. I note,
however, that when considering that issue, the Court refers
to the power of the federal appeals courts to promulgate su-
pervisory rules. See ante, at 11. Like the Court (and
JUSTICE BARRETT), I recognize that the Government “does
not challenge the general existence of the Court of Appeals’
 Cite as: 595 U. S. ____ (2022) 17

BREYER, J., dissenting

supervisory power.” Ibid., n. 1. I would add that our prec-
edents clearly recognize the existence of such a power. See,
e.g., Thomas v. Arn, 474 U. S. 140, 146 (1985) (“It cannot be
doubted that the courts of appeals have supervisory powers
that permit, at the least, the promulgation of procedural
rules governing the management of litigation”); United
States v. Hasting, 461 U. S. 499, 505 (1983) (“[I]n the exer-
cise of supervisory powers, federal courts may, within lim-
its, formulate procedural rules not specifically required by
the Constitution or the Congress”). I would also add that
“[o]ur review of rules adopted by the courts of appeals” pur-
suant to this power “is limited in scope.” Ortega-Rodriguez
v. United States, 507 U. S. 234, 244 (1993). And I do not
find that surprising. A degree of authority for the courts of
appeals, closer to the fray, to issue at least some supervi-
sory rules facilitates the flexibility needed in our geograph-
ically dispersed multicircuit system.
* * *
For these reasons, with respect, I dissent.