Illinois Official Reports
Appellate Court
People v. Floyd, 2014 IL App (2d) 120507
Appellate Court THE PEOPLE OF THE STATE OF ILLINOIS, Plaintiff-Appellee, v.
Caption CHRYSTAL L. FLOYD, Defendant-Appellant.
District & No. Second District
Docket No. 2-12-0507
Filed March 28, 2014
Rehearing denied July 11, 2014
Held In defendant’s prosecution for aggravated driving under the influence,
(Note: This syllabus the probative value of the retrograde extrapolation calculation used to
constitutes no part of the establish her blood alcohol concentration at the time she was arrested
opinion of the court but was outweighed by the prejudicial effect of that evidence, and,
has been prepared by the therefore, her conviction was reversed and the cause was remanded for
Reporter of Decisions a new trial, notwithstanding the premise that a person’s BAC
for the convenience of determined by a breath or blood test at a particular time may be
the reader.)
extrapolated back to the time of an earlier occurrence when the
person’s BAC was higher, since many factors must be considered to
make such a calculation reliable, and in defendant’s case, a “big
assumption” was made that defendant was eliminating alcohol when
she was given a breath test, several relevant factors were not
considered, the State’s expert admitted he was unaware of many
factors necessary to determine whether defendant was eliminating
alcohol, and, under the circumstances, the calculation made in
defendant’s case was unreliable.
Decision Under Appeal from the Circuit Court of Kane County, No. 11-CF-1221; the
Review Hon. Marmarie J. Kostelny, Judge, presiding.
Judgment Reversed and remanded.
Counsel on Alan D. Goldberg and Patrick F. Cassidy, both of State Appellate
Appeal Defender’s Office, of Chicago, for appellant.
Joseph H. McMahon, State’s Attorney, of St. Charles (Lawrence M.
Bauer and Colleen P. Price, both of State’s Attorneys Appellate
Prosecutor’s Office, of counsel), for the People.
Panel JUSTICE HUTCHINSON delivered the judgment of the court, with
opinion.
Justices McLaren and Hudson concurred in the judgment and opinion.
OPINION
¶1 Following a jury trial, defendant, Chrystal L. Floyd, was convicted of aggravated driving
under the influence (DUI) pursuant to section 11-501(a)(2) of the Illinois Vehicle Code (625
ILCS 5/11-501(a)(2) (West 2010)) and resisting arrest (720 ILCS 5/31-1(a) (West 2010)).
During the trial, the State introduced expert witness testimony on a “retrograde extrapolation”
calculation in an attempt to demonstrate that defendant’s blood alcohol concentration (BAC)
was at or above 0.08 at the time of her arrest. Retrograde extrapolation is premised on the
theory that a person’s BAC, derived from a breath or blood test at a particular time, can be
extrapolated back to an allegedly higher BAC that existed at the time of a prior incident. The
State also introduced evidence of other crimes that occurred before defendant allegedly
committed the offense of aggravated DUI.
¶2 On appeal, defendant contends that the trial court erred by (1) allowing the expert witness’s
testimony on retrograde extrapolation when the expert did not have information necessary to
conduct a reliable calculation; (2) allowing the State to admit other-crimes evidence that was
highly prejudicial, but minimally relevant; (3) allowing testimony, which lacked foundation,
that defendant failed a horizontal gaze nystagmus (HGN) test; and (4) failing to instruct the
jury that it could not draw a negative inference from the State’s video recording of defendant’s
field sobriety tests, which the State failed to produce. For the following reasons, we reverse
defendant’s DUI conviction and remand for a new trial.
¶3 The record reflects that, on June 16, 2011, defendant was in the parking lot at the Dolphin
Cove Family Aquatic Center in Carpentersville. At approximately 7:30 p.m., defendant made a
911 call via the OnStar system in her vehicle. Defendant told the 911 operator that she had a
“violent boyfriend” who wanted to hit and rob her. Defendant can be heard on the recording
telling a man that she had been “drinking since I’ve been here.” Defendant then told the
operator that a man who made her perform oral sex on him was sitting in her vehicle and that
“he needs to get the [expletive] out of my car.” Officer David Rowley was dispatched to the
Dolphin Cove parking lot. Upon arriving, he observed defendant and a man arguing outside of
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a vehicle. Because Rowley believed that defendant was intoxicated, he told her not to drive. At
that point, defendant and the man went separate ways, and Rowley left the scene.
¶4 Thereafter, Mike Eschenbach, the manager of Dolphin Cove, noticed that defendant was
back inside her vehicle. Defendant was alone, sitting in the passenger seat, and listening to
loud music. Eschenbach observed a man approach defendant’s vehicle, and the man then
“tossed something at the vehicle, gave it a light shake, and walked away.” Eschenbach left the
Dolphin Cove parking lot at approximately 8:30 p.m.
¶5 At around 8:50 p.m., Don Azerela, the building supervisor, witnessed a man approach
defendant’s vehicle. About a minute later, Azerela heard the man pounding on defendant’s
vehicle and saw the vehicle shake. Azerela moved closer to the parking lot and was joined by
Scott McManus. As the man was shaking the vehicle, Azerela and McManus witnessed the
vehicle’s brake lights come on and heard the engine start. A chase ensued and McManus called
911. Azerela estimated that the vehicle reached a speed of 25 miles per hour during the chase.
When the man ran toward a gas station, defendant’s vehicle turned back and returned to its
original parking space. The police arrived about a minute later.
¶6 Officer Robert Drews arrived at the scene and observed skid marks leading to the parked
vehicle. The key was in the ignition, but the engine was not running, and defendant appeared to
be sleeping in the driver’s seat. Drews knocked on the window, and when defendant opened
the vehicle’s door, Drews could smell a “moderate” odor of alcohol. According to Drews,
defendant’s speech was “good,” and her eyes were not bloodshot or glassy. Defendant told
Drews that she had not been driving, because she was too drunk to drive. Drews advised
defendant that she needed to perform sobriety tests, but defendant refused and began to walk
away. Drews attempted to arrest defendant, but she resisted; Drews and his partner effected the
arrest and placed her into the squad vehicle. A tow truck subsequently towed defendant’s
vehicle.
¶7 At the police station, defendant agreed to perform field sobriety tests. Defendant passed a
one-legged-stand test but failed a walk-and-turn test. Drews also tested defendant’s eyes for
the presence of HGN. The test looks for three clues per eye: (1) the lack of a smooth pursuit as
a stimulus is moved from directly ahead of the subject to the subject’s periphery; (2) the
presence of a “distinct nystagmus at maximum deviation” when the stimulus is held as far out
to the periphery as the eye can follow; and (3) the onset of nystagmus before the eye has rotated
45 degrees as it follows the stimulus toward the periphery. The maximum number of clues that
can be detected is six, with three clues for each eye. Drews determined that four clues were
present and concluded that defendant was under the influence of alcohol.
¶8 All three tests were performed in the police station’s booking area. The booking area
contained video recording devices in the booking room, the sally port, and the hallway leading
to the booking room.
¶9 Law enforcement officers administered a breath test to defendant at 10:30 p.m., which
registered her BAC at 0.069. At trial, the State produced John Wetstein, a forensic toxicologist,
as an expert witness. Wetstein testified that, after conducting a retrograde extrapolation
calculation, he determined that defendant’s BAC at 9:10 p.m. was between 0.082 and 0.095.
¶ 10 Wetstein explained that conducting a retrograde extrapolation calculation is possible
because a person eliminates alcohol at a fixed rate of between 0.01 and 0.02 grams per deciliter
of blood per hour. Wetstein explained that two conditions must be met for the calculation to be
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valid. First, the person metabolizes alcohol at the normal rate. Second, the person is in the
postabsorption phase–that is, the person is no longer absorbing alcohol and is in the
elimination phase–when the breath test is administered. Wetstein explained that, because the
body absorbs alcohol primarily through the small intestine, a person’s absorption rate will vary
depending on many factors. These factors include the type of food that the person has eaten,
the type of alcohol consumed, and the length of time during which the drinking occurred.
Wetstein testified that after a person’s last drink a person can take from 15 minutes to 90
minutes or more to enter the postabsorption phase.
¶ 11 On cross-examination, Wetstein acknowledged that he did not know what defendant had
eaten that night, how long she had been drinking, or what type of alcohol she consumed.
Wetstein admitted that he did not attempt to determine when defendant had entered the
elimination phase but, rather, assumed that she was in the elimination phase at 9:10 p.m.
Wetstein explained that, if a person had not consumed any alcohol since 7:30 p.m., he would
be “quite confident” that the person was in the elimination phase by 9:10 p.m.
¶ 12 The jury found defendant guilty of aggravated DUI and resisting arrest. Based on two prior
burglary convictions, the trial court sentenced defendant as a Class X offender to the minimum
of six years’ imprisonment. Defendant appeals her DUI conviction but not her resisting arrest
conviction.
¶ 13 Defendant’s first contention on appeal is that the trial court erred in admitting Wetstein’s
testimony regarding Wetstein’s retrograde extrapolation calculation. Defendant argues that,
because Wetstein did not have information necessary to perform a retrograde extrapolation
calculation with any degree of certainty, the prejudicial effect of his testimony outweighed its
probative value. Specifically, defendant argues that Wetstein did the “simple part” of the
retrograde extrapolation calculation by adding between 0.01 and 0.02 per hour to the result of
defendant’s breath test, but he “assumed away” that defendant was in the postabsorption,
elimination phase. Thus, the gravamen of defendant’s argument is that, because a subject being
in the elimination phase is necessary for a retrograde extrapolation calculation to be accurate
and valid, Wetstein’s testimony had little probative value because he merely assumed that
defendant was in that phase. Further, Wetstein’s testimony was prejudicial because, as a
“court-pronounced expert regarding retrograde extrapolation,” the jury would “listen[ ] to him
anyway.”
¶ 14 The admissibility of evidence rests in the trial court’s sound discretion, and its ruling will
not be reversed absent an abuse of discretion. People v. Montes, 2013 IL App (2d) 111132,
¶ 61. Under Illinois Rules of Evidence 401 and 402 (eff. Jan. 1, 2011), relevant evidence, i.e.,
evidence that has a tendency to prove or disprove a fact of consequence, is admissible at trial.
Nonetheless, relevant evidence may be excluded if its prejudicial effect substantially
outweighs its probative value. Ill. R. Evid. 403 (eff. Jan. 1, 2011); People v. Hoerer, 375 Ill.
App. 3d 148, 157 (2007). Thus, in deciding whether to admit evidence, the trial court must
weigh the evidence’s prejudicial effect against its probative value. Hoerer, 375 Ill. App. 3d at
157 (citing People v. Walker, 211 Ill. 2d 317, 338 (2004)).
¶ 15 In support of her contention, defendant cites State v. Eighth Judicial District Court, 267
P.3d 777 (Nev. 2011) (Armstong). In Armstrong, the Nevada Supreme Court considered
whether the trial court erred in excluding a retrograde extrapolation calculation to estimate the
defendant’s BAC. Id. at 778-79. The defendant was involved in a vehicular accident at 1:30
a.m. Id. at 779. A single blood sample was taken at 3:51 a.m. and reflected the defendant’s
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BAC as 0.18. Id. After an evidentiary hearing, the trial court granted the defendant’s motion to
exclude the retrograde extrapolation calculation. Id.
¶ 16 In determining whether the trial court erred in excluding the evidence, the Nevada
Supreme Court noted that a retrograde extrapolation calculation required information on the
rates at which alcohol was absorbed and excreted. Id. at 780. It further noted that rates can vary
depending on a number of factors, including the elapsed time between a person’s last drink and
the blood test; the amount and type of alcohol consumed; the time period during which the
alcohol was consumed; and personal characteristics such as age, weight, alcohol tolerance, and
food intake. Id.
¶ 17 After determining that retrograde extrapolation evidence was relevant, the Nevada
Supreme Court turned to whether the evidence unfairly prejudiced the defendant. Id. at 781.
The reviewing court noted that the trial court’s concern centered on the unknown variables,
which suggested:
“[T]he evidence [was] of little probative value given those variables and the single
[blood] sample, but the evidence [was] likely to move the jury to declare guilt based
solely on a reaction to the [BAC] and the very real devastation caused by drunk driving
rather than proof that the defendant was driving under the influence or with a
prohibited blood alcohol level.” Id. at 781-82.
After discussing case law from another jurisdiction, the court in Armstrong opined that
“achieving a reliable extrapolation calculation requires consideration of a variety of factors.”
Id. at 783. Those factors include a subject’s (1) gender; (2) weight; (3) age; (4) height; and (5)
mental state; (6) the type and amount of food in the stomach; (7) the type and amount of
alcohol consumed; (8) the time the last alcoholic drink was consumed; (9) the subject’s
drinking pattern at the relevant time; (10) the elapsed time between the first drink and the last
drink consumed; (11) the elapsed time between the last drink and the blood draws; (12) the
number of samples taken; (13) the elapsed time between the offense and the blood draws; (14)
the average alcohol absorption rate; and (15) the average elimination rate. Id. Turning to the
case before it, the Nevada Supreme Court noted that experts calculated the defendant’s BAC
on factors attributed to the “average person” and “various hypothetical situations.” Id. The
reviewing court noted that some of the above factors were known, such as that the defendant
consumed two beers between 5 p.m. and 10 p.m., that he weighed 212 pounds, and the elapsed
time between the accident and the blood draw. Id. However, there was no evidence concerning
the defendant’s age or height; the type and amount of food in his stomach; and his emotional
state after the accident. Id. In addition, the defendant gave one blood sample. The reviewing
court noted that, although one sample could result in a reliable retrograde extrapolation
calculation if an expert has knowledge of many other personal characteristics and behaviors of
the defendant, a single blood draw, without more information, made it “difficult to determine
whether [the defendant] was absorbing or eliminating alcohol at the time of the blood draw.”
Id. (citing Mata v. State, 41 S.W.3d 902, 916 (Tex. Crim. App. 2001)). The court in Armstrong
concluded:
“The admission of retrograde extrapolation evidence when a single blood draw was
taken more than two hours after the accident is insufficiently tethered to individual
factors necessary to achieve a reliable calculation [and] potentially invites the jury to
determine [the defendant’s] guilt based upon emotion or an improper ground–that the
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defendant had a high blood alcohol level several hours later–rather than a meaningful
evaluation of the evidence.” Id.
Thus, the reviewing court determined that the trial court did not abuse its discretion in
excluding the retrograde extrapolation evidence. Id.
¶ 18 The State, conversely, cites Petraski v. Thedos, 382 Ill. App. 3d 22 (2008). In Petraski,
Margaret Petraski was seriously injured in an accident with a vehicle driven by an officer in the
Cook County sheriff’s department; a jury awarded her in excess of $26 million. Id. at 23-24. At
trial, the defendants sought to introduce expert witness testimony that Petraski’s BAC would
have been above the legal limit at the time of the accident. Id. at 25. The expert would have
testified that, based on a blood test taken 90 minutes after the accident, Petraski had a blood
serum reading of 0.116 grams per deciliter. Id. After conducting a conversion, the expert
would testify that Petraski’s BAC at the time of the accident was approximately 0.095 or
0.096. Id. at 25-26. The expert would testify that he assumed that Petraski was in the
elimination phase during the entire period after the accident, and with that assumption he could
perform a retrograde extrapolation calculation. Id. at 26. The trial court excluded the evidence
as being too speculative. Id.
¶ 19 On appeal, the reviewing court reversed the trial court’s exclusion of the retrograde
extrapolation calculation. The reviewing court concluded:
“We do not believe [the expert’s] assumption that Petraski’s [BAC] was in the
elimination phase when her blood was drawn [was] unwarranted. The blood draw took
place at least [an hour and a half] after the collision, most probably longer than that.
Nowhere in [the expert’s] proposed testimony was he asked to offer an estimate of
Petraski’s [BAC] level if she were in the absorption phase at the time of the draw. Nor
did the plaintiff offer any such evidence.” Id. at 31-32.
The reviewing court concluded that any questions regarding the facts upon which the expert
based his opinion would go to the weight of his opinion, which could be challenged on
cross-examination. Id. at 32. The reviewing court further concluded that the expert’s
testimony, which would have created a presumption of intoxication, would have been
“extremely probative of whether [Petraski] was partially at fault for the accident,” particularly
when the jury had already concluded that Petraski was 25% negligent. Id. With respect to
unfair prejudice, the reviewing court found that there was an “insubstantial risk” that the jury
would have misused the evidence. Id. at 33. Thus, the reviewing court reversed and remanded
for a new trial. Id.
¶ 20 We are persuaded by the Nevada Supreme Court’s thoughtful and detailed reasoning in
Armstrong. A retrograde extrapolation calculation based on a single breath test, and when
many of the factors necessary to determine whether the defendant was in the elimination phase
are unknown, is insufficient to provide a reliable calculation and invites the jury to determine
guilt on an improper basis. Based on the specific circumstances presented in this case, we
believe that the prejudicial effect of the retrograde extrapolation calculation substantially
outweighed its probative value and that the trial court abused its discretion in admitting it.
¶ 21 Before weighing the probative value of the retrograde extrapolation calculation against its
prejudicial effect, we first address the State’s argument that, because Illinois follows the test
enunciated in Frye v. United States, 293 F. 1013 (D.C. Cir. 1923), a trial court does not have
the discretion to exclude scientific evidence due to its prejudicial effect resulting from gaps in
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the scientific evidence. Under the Frye standard, scientific evidence is admissible only if the
methodology or scientific principle is sufficiently established to have gained general
acceptance in a particular field. In re Commitment of Simons, 213 Ill. 2d 523, 529-30 (2004)
(citing Frye, 293 F. at 1014). “General acceptance” does not mean universal acceptance; and
the methodology in question does not need to be accepted by unanimity, consensus, or a
majority of experts. Id. at 530. Rather, the underlying method used to generate an expert’s
opinion must be reasonably relied on by other experts in the relevant field. Id.
¶ 22 While we recognize that Illinois courts follow the Frye standard for the admission of
scientific evidence (see People v. Caballes, 221 Ill. 2d 282, 334 n.1 (2006)), the State’s
assertion that the Frye standard precludes a trial court from weighing the probative value of
scientific evidence against its prejudicial effect is misplaced. Our supreme court has held that,
even if a particular type of scientific evidence has been generally accepted in the scientific
community, its admissibility “in an individual case will depend on the State’s ability to lay a
proper foundation and to demonstrate the qualifications of its witness, subject to the balancing
of probative value with the risk of unfair prejudice.” (Emphasis added.) People v. McKown,
236 Ill. 2d 278, 314 (2010). We further note that, while other Illinois courts have held that
retrograde extrapolation evidence is admissible so long as it is presented by a qualified expert
(People v. Ikerman, 2012 IL App (5th) 110299, ¶ 38), defendant did not raise the issue of
whether retrograde extrapolation evidence satisfies Frye. Therefore, we emphasize that our
opinion today does not speak to that question.
¶ 23 With respect to the retrograde extrapolation’s probative value, we recognize that
Wetstein’s calculation would be relevant to whether defendant’s BAC was at or above 0.08.
Nonetheless, the inherent unreliability of Wetstein’s calculation is reflected in his own
testimony. Specifically, Wetstein testified that determining whether a person was in the
elimination phase was a “complicated question.” Wetstein testified that different
circumstances could affect whether someone was in the elimination phase, such as when the
person started and stopped drinking; a person’s eating and drinking habits; how much and what
food had been consumed; and the type of alcohol consumed. Wetstein acknowledged that he
did not recall when defendant started and stopped drinking. He testified that, if other relevant
information on whether defendant was in the elimination phase were available, he would have
factored it into his calculation. However, Wetstein’s testimony is devoid of any indication that
he considered any other information to determine whether defendant was in the elimination
phase. Instead, Wetstein admitted that his “big assumption” was that defendant was
eliminating alcohol when law enforcement officers administered the breath test, and he
admitted that if his assumption were wrong “the extrapolation [would not] be valid.” Thus,
because Wetstein’s calculation was premised on the assumption that defendant was in the
elimination phase, without consideration of other relevant factors and without additional
breath tests, we find the probative value of his testimony to be significantly diminished. See
Armstrong, 267 P.3d at 783.
¶ 24 Conversely, the risk of unfair prejudice from Wetstein’s calculation was substantial.
Illinois courts have defined “unfair prejudice” as an “ ‘ “undue tendency to suggest decision on
an improper basis, commonly an emotional one, such as sympathy, hatred, contempt, or
horror.” ’ ” People v. Barnes, 2013 IL App (1st) 112873, ¶ 44 (quoting People v. Eyler, 133 Ill.
2d 173, 218 (1989), quoting Michael H. Graham, Cleary and Graham’s Handbook of Illinois
Evidence § 403.1 (4th ed. 1984)). In this case, we find the reasoning in Armstrong applicable.
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The introduction of Wetstein’s retrograde extrapolation calculation, when many necessary
factors were unknown and when only one breath test was administered, invited the jury to
convict her due to a reaction to a supposedly high BAC rather than proof beyond a reasonable
doubt that defendant was driving under the influence. See Armstrong, 267 P.3d at 781.
¶ 25 We emphasize that our holding is limited to the specific circumstances of this case, and we
recognize that retrograde extrapolation “has its place in proving that a defendant was driving
under the influence.” Id. at 783-84. In doing so, we further emphasize that we are not creating
a blueprint or a bright-line rule for the admissibility of retrograde extrapolation evidence. As
the court in Armstrong noted, not every factor must be known to construct a reliable
extrapolation; rather, the various factors must be balanced. Id. at 783. Whether the State
produces a reliable extrapolation will depend on the specific circumstances of each case.
¶ 26 We are also cognizant of the State’s concern that many of the factors necessary to
determine if a person was in the elimination phase will be difficult to obtain if that person
invokes his or her privilege against self-incrimination. Nonetheless, we believe that the State
could still reliably conclude that a defendant was in the elimination phase by conducting
additional breath or blood tests. As the court in Mata opined:
“If the State had more than one test, each test a reasonable length of time apart, and the
first test [was] conducted within a reasonable time from the time of the offense, an
expert could potentially create a reliable estimate of the defendant’s BAC with limited
knowledge of personal characteristics and behaviors.” Mata, 46 S.W.3d at 916.
¶ 27 In sum, because the State’s expert witness acknowledged that he was unaware of many of
the factors necessary to determine whether defendant was in the elimination phase, and
because the police conducted only one BAC test, we find the extrapolation calculation to be
inherently unreliable. In addition, because the extrapolation evidence invited the jury to
convict defendant on the basis of a supposedly high BAC, the potential for prejudice from
admitting that evidence was high. Because the prejudicial effect of the extrapolation
substantially outweighed the probative value, the trial court abused its discretion in admitting
the evidence. See generally McKown, 236 Ill. 2d at 314 (noting that the admissibility of
scientific evidence is subject to the balancing of probative value and the risk of unfair
prejudice). Further, given the conflicting nature of the other testimony at trial, including that
defendant passed some field sobriety tests while failing others, the trial court’s admission of
the extrapolation evidence was not harmless. See id. at 311 (rejecting a harmless error
argument).
¶ 28 Nonetheless, although we are reversing, we find that, after viewing the evidence in the light
most favorable to the State, there was sufficient evidence from which the jury could have
found defendant guilty of aggravated DUI beyond a reasonable doubt. See People v. Lopez,
229 Ill. 2d 322, 366-67 (2008) (noting that the relevant inquiry into whether double jeopardy
prohibits another trial is whether, after viewing the evidence in the light most favorable to the
State, including suppressed evidence, any rational trier of fact could have found the essential
elements of the crime beyond a reasonable doubt). The evidence in this case included the
improperly admitted extrapolation evidence, the field sobriety tests, and Drew’s opinion
testimony.
¶ 29 Finally, while we note that defendant has raised other issues on appeal, we decline to
review them. “As a general rule, a court of review will not decide moot or abstract questions or
render advisory opinions.” People v. Campa, 217 Ill. 2d 243, 269 (2005).
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¶ 30 For the foregoing reasons, we reverse the judgment of the circuit court of Kane County and
remand for a new trial.
¶ 31 Reversed and remanded.
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