delivered the opinion of the Court.
The Federal Magistrates Act grants district courts authority to assign magistrates certain described functions as well as “such additional duties as are not inconsistent with the Constitution and laws of the United States.”1 In Gomez v. United States, 490 U. S. 858 (1989), we held that those “additional duties” do not encompass the selection of a jury in a *925felony trial without the defendant’s consent. In this case, we consider whether the defendant’s consent warrants a different result.
I
Petitioner and a codefendant were charged with importing four kilograms of heroin. At a pretrial conference attended by both petitioner and his counsel, the District Judge asked if there was “[a]ny objection to picking the jury before a magistrate?” App. 2. Petitioner’s counsel responded: “I would love the opportunity.” Ibid. Immediately before the jury selection commenced, the Magistrate asked for, and received, assurances from counsel for petitioner and from counsel for his codefendant that she had their clients’ consent to proceed with the jury selection.2 She then proceeded to conduct the voir dire and to supervise the selection of the jury. Neither defendant asked the District Court to review any ruling made by the Magistrate.
The District Judge presided at the jury trial, which resulted in the conviction of petitioner and the acquittal of his codefendant. In the District Court, petitioner raised no objection to the fact that the Magistrate had conducted the voir dire. On appeal, however, he contended that it was error to assign the jury selection to the Magistrate and that our decision in Gomez required reversal. The Court of Appeals disagreed. Relying on its earlier decision in United States v. Musacchia, 900 F. 2d 493 (CA2 1990), it held “that explicit consent by a defendant to magistrate-supervised voir dire waives any subsequent challenge on those grounds,” and affirmed petitioner’s conviction. App. to Pet. for Cert. 2a; 904 F. 2d 34 (1990) (affirmance order).
*926In Musacchia, the Second Circuit had affirmed a conviction in a case in which the defendant had not objected to jury selection by the Magistrate. The Court of Appeals concluded that our holding in Gomez applied only to cases in which the magistrate had acted without the defendant’s consent. The court explained:
“Appellants additionally claim that Gomez states that a magistrate is without jurisdiction under the Federal Magistrates Act to conduct voir dire. We disagree. Since Gomez was decided we and other circuits have focused on the ‘without defendant’s consent’ language and generally ruled that where there is either consent or a failure to object a magistrate may conduct the jury voir dire in a felony case. See [United States v. Vanwort, 887 F. 2d 375, 382-383 (CA2 1989), cert. denied sub nom. Chapoteau v. United States, 495 U. S. 906 (1990); United States v. Mang Sun Wong, 884 F. 2d 1537, 1544 (CA2 1989), cert. denied, 493 U. S. 1082 (1990); United States v. Lopez-Pena, 912 F. 2d 1542, 1545-1548 (CA1 1989)] (not plain error to permit magistrate to preside since objection to magistrate must be raised or it is waived); Government of the Virgin Islands v. Williams, 892 F. 2d 305, 310 (3d Cir. 1989) (absent demand no constitutional difficulty under § 636(b)(3) with delegating jury selection to magistrate); United States v. Ford, 824 F. 2d 1430, 1438-39 (5th Cir. 1987) (en banc) (harmless error for magistrate to conduct voir dire where defendant failed to object), cert. denied, 484 U. S. 1034 . . . (1988); United States v. Wey, 895 F. 2d 429 (7th Cir. 1990) (jury selection by magistrate is not plain error where no prejudice is shown). Concededly, [United States v. France, 886 F. 2d 223 (CA9 1989),] concluded otherwise. The court there ruled that defendant’s failure to contemporaneously object to the magistrate conducting jury selection did not waive her right to appel*927late review. 886 F. 2d at 226. But that holding may be explained, as noted earlier, by what the court perceived as the futility of defendant raising an objection below.” 900 F. 2d, at 502.
The conflict among the Circuits described by the Court of Appeals prompted us to grant the Government’s petition for certiorari in the France case, see United States v. France, 495 U. S. 903 (1990). Earlier this Term, we affirmed that judgment by an equally divided Court, United States v. France, 498 U. S. 335 (1991). Thereafter, we granted cer-tiorari in this case and directed the parties to address the following three questions:
“1. Does 28 U. S. C. §636 permit a magistrate to conduct the voir dire in a felony trial if the defendant consents?
“2. If 28 U. S. C. § 636 permits a magistrate to conduct a felony trial voir dire provided that the defendant consents, is the statute consistent with Article III?
“3. If the magistrate’s supervision of the voir dire in petitioner’s trial was error, did the conduct of petitioner and his attorney constitute a waiver of the right to raise this error on appeal?” See 498 U. S. 1066 (1991).
Resolution of these questions must begin with a review of our decision in Gomez.
II
Our holding in Gomez was narrow. We framed the question presented as “whether presiding at the selection of a jury in a felony trial without the defendant's consent is among those ‘additional duties’” that district courts may assign to magistrates. 490 U. S., at 860 (emphasis added). We held that a magistrate “exceeds his jurisdiction” by selecting a jury “despite the defendant’s objection.” Id., at 876. Thus, our holding was carefully limited to the situation in which the *928parties had not acquiesced at trial to the magistrate’s role.3 This particular question had divided the Courts of Appeals. See id., at 861-862, and n. 7. On the other hand, those courts had uniformly rejected challenges to a magistrate’s authority to conduct the voir dire when no objection to his performance of the duty had been raised in the trial court.4
Although we concluded that the role assumed by the Magistrate in Gomez was beyond his authority under the Act, we recognized that Congress intended magistrates to play an integral and important role in the federal judicial system. See id., at 864-869 (citing H. R. Rep. No. 96-287, p. 5 (1979)). Our recent decisions have continued to acknowledge the importance Congress placed on the magistrate’s role. See, e. g., McCarthy v. Bronson, 500 U. S. 136, 142 (1991). “Given the bloated dockets that district courts have now come to expect as ordinary, the role of the magistrate in today’s federal judicial system is nothing less than indispensable.” Government of the Virgin Islands v. Williams, 892 F. 2d 305, 308 (CA3 1989).5
*929Cognizant of the importance of magistrates to an efficient federal court system, we were nonetheless propelled towards our holding in Gomez by several considerations. Chief among our concerns was this Court’s “settled policy to avoid an interpretation of a federal statute that engenders constitutional issues.” Gomez, 490 U. S., at 864. This policy was implicated in Gomez because of the substantial question whether a defendant has a constitutional right to demand that an Article III judge preside at every critical stage of a felony trial.6 The principle of constitutional avoidance led *930us to demand clear evidence that Congress actually intended to permit magistrates to take on a role that raised a substantial constitutional question. Cf. Rust v. Sullivan, 500 U. S. 173, 223 (O’Connor, J., dissenting). The requirement that Congress express its intent clearly was also appropriate because the Government was asking us in Gomez to construe a general grant of authority to authorize a procedure that deprived an individual of an important privilege, if not a right. See 2A C. Sands, Sutherland on Statutory Construction § 58.04, p. 715 (rev. 4th ed. 1984). The lack of an express provision for de novo review, coupled with the absence of any mention in the statute’s text or legislative history of a magistrate’s conducting voir dire without the parties’ consent, convinced us that Congress had not clearly authorized the delegation involved in Gomez. In view of the constitutional issues involved, and the fact that broad language was being construed to deprive a defendant of a significant right or privilege, we considered the lack of a clear authorization dispositive. See Gomez, 490 U. S., at 872, and n. 25, 875-876.
Reinforcing this conclusion was the principle that “[a]ny additional duties performed pursuant to a general authorization in the statute reasonably should bear some relation to the specified duties” that the statute assigned to magistrates.7 Carefully reviewing the duties that magistrates *931were expressly authorized to perform, see id., at 865-871, we focused on the fact that those specified duties that were comparable to jury selection in a felony trial could be performed only with the consent of the litigants.8 We noted that, in 1968 when magistrates were empowered to try “minor offenses,” the exercise of that jurisdiction in any specific case was conditioned upon the defendant’s express written consent. See id., at 866. Similarly, the 1976 amendment provided that a magistrate could be designated as a special master in any civil case but only with the consent of the parties. Id., at 867-868. And in 1979, when Congress enlarged the magistrate’s criminal jurisdiction to encompass all misdemeanors, the exercise of that authority was subject to the defendant’s consent. As we explained:
“A critical limitation on this expanded jurisdiction is consent. As amended in 1979, the Act states that ‘neither the district judge nor the magistrate shall attempt to persuade or induce any party to consent to reference of any civil matter to a magistrate.’ 93 Stat. 643, 28 U. S. C. § 636(c)(2). In criminal cases, the Government may petition for trial before a district judge. ‘Defendants charged with misdemeanors can refuse to consent to a magistrate and thus effect the same removal,’ S. Rep. No. 96-74, p. 7 (1979),- for the magistrate’s criminal trial jurisdiction depends on the defendant’s specific, written consent.” Id., at 870-871 (footnote omitted).
*932Because the specified duties that Congress authorized magistrates to perform without the consent of the parties were not comparable in importance to supervision of felony trial voir dire but were instead “subsidiary matters,” id., at 872, we did not waver from our conclusion that a magistrate cannot conduct voir dire over the defendant’s objection.
I — I I — H 1 — (
This case differs critically from Gomez because petitioner’s counsel, rather than objecting to the Magistrate’s role, affirmatively welcomed it. See supra, at 925. The considerations that led to our holding in Gomez do not lead to the conclusion that a magistrate’s “additional duties” may not include supervision of jury selection when the defendant has consented.
Most notably, the defendant’s consent significantly changes the constitutional analysis. As we explain in Part IV, infra, we have no trouble concluding that there is no Article III problem when a district court judge permits a magistrate to conduct voir dire in accordance with the defendant’s consent. The absence of any constitutional difficulty removes one concern that motivated us in Gomez to require unambiguous evidence of Congress’ intent to include jury selection among a magistrate’s additional duties. Petitioner’s consent also eliminates our concern that a general authorization should not lightly be read to deprive a defendant of any important privilege.
We therefore attach far less importance in this case to the fact that Congress did not focus on jury selection as a possible additional duty for magistrates. The generality of the category of “additional duties” indicates that Congress intended to give federal judges significant leeway to experiment with possible improvements in the efficiency of the judicial process that had not already been tried or even foreseen. If Congress had intended strictly to limit these additional duties to *933functions considered in the committee hearings or debates, presumably it would have included in the statute a bill of particulars rather than a broad residuary clause. Construing this residuary clause absent concerns about raising a constitutional issue or depriving a defendant of an important right, we should not foreclose constructive experiments that are acceptable to all participants in the trial process and are consistent with the basic purposes of the statute.
Of course, we would still be reluctant, as we were in Gomez, to construe the additional duties clause to include responsibilities of far greater importance than the specified duties assigned to magistrates. But the litigants’ consent makes the crucial difference on this score as well. As we explained in Part II, supra, the duties that a magistrate may perform over the parties’ objections are generally subsidiary matters not comparable to supervision of jury selection. However, with the parties’ consent, a district judge may delegate to a magistrate supervision of entire civil and misdemeanor trials. These duties are comparable in responsibility and importance to presiding over voir dire at a felony trial.
We therefore conclude that the Act’s “additional duties” clause permits a magistrate to supervise jury selection in a felony trial provided the parties consent. In reaching this result, we are assisted by the reasoning of the Courts of Appeals for the Second, Third, and Seventh Circuits, all of which, following our decision in Gomez, have concluded that the rationale of that opinion does not apply when the defendant has not objected to the magistrate’s conduct of the voir dire. See United States v. Musacchia, 900 F. 2d 493 (CA2 1990); United States v. Wey, 895 F. 2d 429 (CA7 1990); Government of the Virgin Islands v. Williams, 892 F. 2d 305 (CA3 1989).
We share the confidence expressed by the Third Circuit in Williams that this reading of the additional duties clause strikes the balance Congress intended between the interests *934of the criminal defendant and the policies that undergird the Federal Magistrates Act. Id., at 311. The Act is designed to relieve the district courts of certain subordinate duties that often distract the courts from more important matters.9 Our reading of the “additional duties” clause will permit the courts, with the litigants’ consent, to “continue innovative ex-perimentations” in the use of magistrates to improve the efficient administration of the courts’ dockets. See H. R. Rep. No. 94-1609, p. 12 (1976).10
At the same time, the requirement that a criminal defendant consent to the additional duty of jury selection protects a defendant’s interest in requesting the presence of a judge at all critical stages of his felony trial.
“If a criminal defendant, together with his attorney, believes that the presence of a judge best serves his interests during the selection of the jury, then Gomez preserves his right to object to the use of a magistrate. Where, on the other hand, the defendant is indifferent as to whether a magistrate or a judge should preside, then *935it makes little sense to deny the district court the opportunity to delegate that function to a magistrate, particularly if such a delegation sensibly advances the court’s interest in the efficient regulation of its docket.” Government of the Virgin Islands v. Williams, 892 F. 2d, at 311.
In sum, the structure and purpose of the Federal Magistrates Act convince us that supervision of voir dire in a felony proceeding is an additional duty that may be delegated to a magistrate under 28 U. S. C. § 636(b)(3) if the litigants consent.11 The Act evinces a congressional belief that magistrates are well qualified to handle matters of similar importance to jury selection but conditions their authority to accept such responsibilities on the consent of the parties. If a defendant perceives any threat of injury from the absence of an Article III judge in the jury selection process, he need only decline to consent to the magistrate’s supervision to ensure that a judge conduct the voir dire.12 However, when a *936defendant does consent to the magistrate’s role, the magistrate has jurisdiction to perform this additional duty.
I — I <1
There is no constitutional infirmity in the delegation of felony trial jury selection to a magistrate when the litigants consent. As we have already noted, it is arguable that a defendant in a criminal trial has a constitutional right to demand the presence of an Article III judge at voir dire. We need not resolve that question now, however, to determine that a defendant has no constitutional right to have an Article III judge preside at jury selection if the defendant has raised no objection to the judge’s absence.
We have previously held that litigants may waive their personal right to have an Article III judge preside over a civil trial. See Commodity Futures Trading Comm’n v. Schor, 478 U. S. 833, 848 (1986). The most basic rights of criminal defendants are similarly subject to waiver. See, e. g., United States v. Gagnon, 470 U. S. 522, 528 (1985) (absence of objection constitutes waiver of right to be present at all stages of criminal trial); Levine v. United States, 362 U. S. 610, 619 (1960) (failure to object to closing of courtroom is waiver of right to public trial); Segurola v. United States, 275 U. S. 106, 111 (1927) (failure to object constitutes waiver of Fourth Amendment right against unlawful search and seizure); United States v. Figueroa, 818 F. 2d 1020, 1025 (CA1 1987) (failure to object results in forfeiture of claim of unlawful postarrest delay); United States v. Bascaro, 742 F. 2d 1335, 1365 (CA11 1984) (absence of objection is waiver of double jeopardy defense), cert. denied sub nom. Hobson v. United States, 472 U. S. 1017 (1985); United States v. Coleman, 707 F. 2d 374, 376 (CA9) (failure to object constitutes waiver of Fifth Amendment claim), cert. denied, 464 U. S. 854 (1983). See generally Yakus v. United States, 321 U. S. 414, 444 (1944) (“No procedural principle is more familiar to this Court than that a constitutional right may be forfeited in *937criminal as well as civil cases by the failure to make timely assertion of the right”)- Just as the Constitution affords no protection to a defendant who waives these fundamental rights, so it gives no assistance to a defendant who fails to demand the presence of an Article III judge at the selection of his jury.
Even assuming that a litigant may not waive structural protections provided by Article III, see Schor, 478 U. S., at 850-851, we are convinced that no such structural protections are implicated by the procedure followed in this case. Magistrates are appointed and subject to removal by Article III judges. See 28 U. S. C. § 631. The “ultimate decision” whether to invoke the magistrate’s assistance is made by the district court, subject to veto by the parties. See United States v. Raddatz, 447 U. S. 667, 683 (1980). The decision whether to empanel the jury whose selection a magistrate has supervised also remains entirely with the district court. Because “the entire process takes place under the district court’s total control and jurisdiction,” id., at 681, there is no danger that use of the magistrate involves a “congressional attemptt] ‘to transfer jurisdiction [to non-Article III tribunals] for the purpose of emasculating’ constitutional courts, National Insurance Co. v. Tidewater Co., 337 U. S. 582, 644 (1949) (Vinson, C. J., dissenting) . . . .” Schor, 478 U. S., at 850.
In Raddatz, we held that the Constitution was not violated by the reference to a Magistrate of a motion to suppress evidence in a felony trial. The principal constitutional argument advanced and rejected in Raddatz was that the omission of a requirement that the trial judge must hear the testimony of the witnesses whenever a question of credibility arises violated the Due Process Clause of the Fifth Amendment. Petitioner has not advanced a similar argument in this case, no doubt because it would plainly be foreclosed by our holding in Raddatz. That case also disposes of the Article III argument that petitioner does raise. The reasoning *938in Justice Blackmun’s concurring opinion is controlling here:
“As the Court observes, the handling of suppression motions invariably remains completely in the control of the federal district court. The judge may initially decline to refer any matter to a magistrate. When a matter is referred, the judge may freely reject the magistrate’s recommendation. He may rehear the evidence in whole or in part. He may call for additional findings or otherwise ‘recommit the matter to the magistrate with instructions.’ See 28 U. S. C. §636(b)(1). Moreover, the magistrate himself is subject to the Art. Ill judge’s control. Magistrates are appointed by district judges, § 631(a), and subject to removal by them, § 631(h). In addition, district judges retain plenary authority over when, what, and how many pretrial matters are assigned to magistrates, and ‘[e]ach district court shall establish rules pursuant to which the magistrates shall discharge their duties.’ § 636(b)(4). . . .
“It is also significant that the Magistrates Act imposes significant requirements to ensure competency and impartiality, §§ 631(b), (c), and (i), 632, 637 (1976 ed. and Supp. II), including a rule generally barring reduction of salaries of full-time magistrates, § 634(b). Even assuming that, despite these protections, a controversial matter might be delegated to a magistrate who is susceptible to outside pressures, the district judge — insulated by life tenure and irreducible salary — is waiting in the wings, fully able to correct errors. Under these circumstances, I simply do not perceive the threat to the judicial power or the independence of judicial decisionmaking that underlies Art. III. We do not face a procedure under which ‘Congress [has] delegate[d] to a non-Art. Ill judge the authority to make final determinations on issues of fact.’ Post, at 703 (dissenting opinion). Rather, we confront a procedure under which Congress has vested *939in Art. Ill judges the discretionary power to delegate certain functions to competent and impartial assistants, while ensuring that the judges retain complete supervisory control over the assistants’ activities.” 447 U. S., at 685-686.
Unlike the provision of the Federal Magistrates Act that we upheld in Raddatz, § 636(b)(3) contains no express provision for de novo review of a magistrate’s rulings during the selection of a jury. This omission, however, does not alter the result of the constitutional analysis. The statutory provision we upheld in Raddatz provided for de novo review only when a party objected to the magistrate’s findings or recommendations. See 28 U. S. C. § 636(b)(1). Thus, Raddatz established that, to the extent “de novo review is required to satisfy Article III concerns, it need not be exercised unless requested by the parties.” United States v. Peacock, 761 F. 2d 1313, 1318 (CA9) (Kennedy, J.), cert. denied, 474 U. S. 847 (1985). In this case, petitioner did not ask the District Court to review any ruling by the Magistrate. If a defendant in a future case does request review, nothing in the statute precludes a district court from providing the review that the Constitution requires. Although there may be other cases in which de novo review by the district court would provide an inadequate substitute for the Article III judge’s actual supervision of the voir dire, the same is true of a magistrate’s determination in a suppression hearing, which often turns on the credibility of witnesses. See Raddatz, 447 U. S., at 692 (Stewart, J., dissenting). We presume, as we did in Raddatz when we upheld the provision allowing reference to a magistrate of suppression motions, that district judges will handle such cases properly if and when they arise. See id., at 681, n. 7. Our decision that the procedure followed in Raddatz comported with Article III therefore requires the same conclusion respecting the procedure followed in this case.
*940V
Our disposition of the statutory and constitutional questions makes it unnecessary to discuss the third question that we asked the parties to brief and to argue. We note, however, that the Solicitor General conceded that it was error to make the reference to the Magistrate in this case and relied entirely on the argument that the error was waived. Although that concession deprived us of the benefit of an adversary presentation, it of course does not prevent us from adopting the legal analysis of those Courts of Appeals that share our interpretation of the statute as construed in Gomez. We agree with the view of the majority of Circuit Judges who have considered this issue, both before and after our decision in Gomez, that permitting a magistrate to conduct the voir dire in a felony trial when the defendant raises no objection is entirely faithful to the congressional purpose in enacting and amending the Federal Magistrates Act.13
The judgment of the Court of Appeals is affirmed.
It is so ordered.
Pub. L. 90-578, 82 Stat. 1108, as amended, 28 U. S. C. § 636(b)(3).
“THE COURT: Mr. Breitbart, I have the consent of your client to proceed with the jury selection?
“MR. BREITBART: Yes, your Honor.
“THE COURT: And Mr. Lopez, do I have the consent of your client to proceed?
“MR. LOPEZ: Yes, your Honor.” App. 5.
As the Third Circuit has recognized:
“The Court did not, however, reach the question presented in this case: whether the Federal Magistrates Act permits a magistrate to preside over the selection of a jury when a defendant consents. In Gomez, the Court framed the issue as ‘whether presiding at the selection of a jury in a felony trial without the defendant’s consent’ is an additional duty within the meaning of the Federal Magistrates Act. [490 U. S., at 860] (emphasis added); see also id. at [876] (rejecting the government’s harmless error analysis on the grounds that it ‘does not apply in a felony case in which, despite the defendant’s objection and without any meaningful review by a district judge, an officer exceeds his jurisdiction by selecting a jury’). Gomez thus left open the question whether a defendant’s consent makes a difference as to whether a district court may assign voir dire to a magistrate.” Government of the Virgin Islands v. Williams, 892 F. 2d 305, 308-309 (1989).
See, e. g., United States v. Ford, 824 F. 2d 1430 (CA5 1987) (en banc), cert. denied, 484 U. S. 1034 (1988); United States v. DeFiore, 720 F. 2d 757 (CA2 1983), cert. denied sub nom. Coppola v. United States, 466 U. S. 906 (1984); United States v. Rivera-Sola, 713 F. 2d 866 (CA1 1983); Haith v. United States, 342 F. 2d 158 (CA3 1965).
“It can hardly be denied that the system created by the Federal Magistrates Act has exceeded the highest expectations of the legislators who *929conceived it. In modern federal practice, federal magistrates account for a staggering volume of judicial work. In 1987, for example, magistrates presided over nearly half a million judicial proceedings. See S. Rep. No. 100-293, 100th Cong., 2d Sess. 7, reprinted in 1988 U. S. Code Cong. & Admin. News 5564. As a recent State Report noted, ‘[i]n particular, magistrates [in 1987] conducted over 134,000 preliminary proceedings in felony cases; handled more than 197,000 references of civil and criminal pretrial matters; reviewed more than 6,500 social security appeals and more than 27,000 prisoner filings; and tried more than 95,000 misdemeanors and 4,900 civil cases on consent of the parties. Id. at 5565.” Government of the Virgin Islands v. Williams, 892 F. 2d, at 308.
In Gomez, we cited our opinion in Commodity Futures Trading Comm’n v. Schor, 478 U. S. 833 (1986), which emphasized the importance of the personal right to an Article III adjudicator:
“Article III, § 1, serves both to protect ‘the role of the independent judiciary within the constitutional scheme of tripartite government.’ Thomas v. Union Carbide Agricultural Products Co., 473 U. S. 568, 583 (1985), and to safeguard litigants’ ‘right to have claims decided before judges who are free from potential domination by other branches of government.’ United States v. Will, 449 U. S. 200, 218 (1980). See also Thomas, supra, at 582-583; Northern Pipeline, 458 U. S., at 58. Although our cases have provided us with little occasion to discuss the nature or significance of this latter safeguard, our prior discussions of Article III, § l’s guarantee of an independent and impartial adjudication by the federal judiciary of matters within the judicial power of the United States intimated that this guarantee serves to protect primarily personal, rather than structural, interests. See, e. g., id., at 90 (Rehnquist, J., concurring in judgment) (noting lack of consent to non-Article III jurisdiction); id., at 95 (White, J., dissenting) (same). See also Currie, Bankruptcy Judges and the Independent Judiciary, 16 Creighton L. Rev. 441, 460, n. 108 (1983) (Article III, § 1, ‘was designed as a protection for the parties from the risk of legislative or exec*930utive pressure on judicial decision’). Cf. Crowell v. Benson, [285 U. S. 22, 87 (1932)] (Brandéis, J., dissenting).” Id., at 848.
“The Federal Magistrates Act provides that a ‘magistrate may be assigned such additional duties as are not inconsistent with the Constitution and laws of the United States.’ 28 U. S. C. § 636(b)(3). Read literally and without reference to the context in which they appear, these words might encompass any assignment that is not explicitly prohibited by statute or by the Constitution. . . .
“When a statute creates an office to which it assigns specific duties, those duties outline the attributes of the office. Any additional duties performed pursuant to a general authorization in the statute reasonably should bear some relation to the specified duties. Thus in United States *931v. Raddatz, 447 U. S. 667, 674-676 (1980); Mathews v. Weber, 423 U. S. 261 (1976); and Wingo v. Wedding, 418 U. S. 461 (1974), we interpreted the Federal Magistrates Act in light of its structure and purpose." Gomez v. United States, 490 U. S., at 863-864.
The legislative history of the statute also emphasizes the crucial nature of the presence or absence of the litigants’ consent. See H. R. Rep. No. 96-287, p. 20 (1979) (“Because of the consent requirement, magistrates will be used only as the bench, bar, and litigants desire, only in cases where they are felt by all participants to be competent”).
See, e. g., H. R. Rep. No. 94-1609, p. 7 (1976) (magistrate is to “assist the district judge in a variety of pretrial and preliminary matters thereby facilitating the ultimate and final exercise of the adjudicatory function at the trial of the case”); S. Rep. No. 92-1065, p. 3 (1972) (magistrates “render valuable assistance to the judges of the district courts, thereby freeing the time of those judges for the actual trial of cases”); H. R. Rep. No. 1629, 90th Cong., 2d Sess., p. 12 (1968) (purpose of Act is “to cull from the ever-growing workload of the U. S. district courts matters that are more desirably performed by a lower tier of judicial officers”).
See, e. g., United States v. Peacock, 761 F. 2d 1313, 1319 (CA9) (Kennedy, J.) (“There may be sound reasons ... to allow the magistrate to assist [in voir dire], as was done in this case. [E]ach of the . . . circuits in the federal system . . . has been instructed to improve its efficiency in juror utilization. . . . The practice of delegating voir dire to a magistrate may assist the district courts in accomplishing this objective”), cert. denied, 474 U. S. 847 (1985).
We noted in Gomez that the legislative history of the Act nowhere listed supervision, without a defendant’s consent, of a felony trial voir dire as a potential magistrate responsibility. We did call attention, however, to a Committee Report that referred to a “letter suggesting] that a magistrate selected juries only tvith consent of the parties.” Gomez v. United States, 490 U. S. 858, 875-876, n. 30 (1989) (emphasis added) (citing H. R. Rep. No. 94-1609, p. 9 (1976)).
We do not qualify the portion of our opinion in Gomez that explained why jury selection is an important function, the performance of which may be difficult for a judge to review with infallible accuracy. See 490 U. S., at 873-876. We are confident, however, that defense counsel can sensibly balance these considerations against other concerns in deciding whether to object to a magistrate’s supervision of voir dire. We stress, in this regard, that defendants may waive the right to judicial performance of other important functions, including the conduct of the trial itself in misdemeanor and civil proceedings. Like jury selection, these duties require the magistrate to “observe witnesses, make credibility determinations, and weigh contradictory evidence,” id., at 874, n. 27, and therefore present equivalent problems for judicial oversight.
See, e. g., United States v. Alvarado, 923 F. 2d 253 (CA2 1991); Government of the Virgin Islands v. Williams, 892 F. 2d 305 (CA3 1989); United States v. Rivera-Sola, 713 F. 2d 866 (CA1 1983); United States v. Ford, 824 F. 2d, at 1439-1440 (Jolly, J., concurring). Cf. United States v. Wey, 895 F. 2d 429, 431 (CA7 1990) (“it may be that the defendant’s consent could authorize the judge to designate a magistrate, under 28 U. S. C. § 636(b)(3), to preside over jury selection”); Ford, 824 F. 2d, at 1438-1439 (failure to object constitutes waiver of error); United States v. DeFiore, 720 F. 2d 757 (CA2 1983), cert. denied sub nom. Coppola v. United States, 466 U. S. 906 (1984). But see United States v. Martinez-Torres, 912 F. 2d 1552 (CA1 1990) (en banc); United States v. France, 886 F. 2d 223 (CA9 1989).