Mr. Chief Justice Burger
delivered the opinion of the Court.
We granted certiorari, 444 U. S. 824, to resolve the constitutionality of a provision of the Federal Magistrates Act, 28 U. S. C. § 636 (b)(1)(B), which permits a district court to refer to a magistrate a motion to suppress evidence and authorizes the district court to determine and decide such motion based on the record developed before a magistrate, including the magistrate’s proposed findings of fact and recommendations.
I
Respondent Raddatz was indicted on March 31, 1977, in the Northern District of Illinois for unlawfully receiving a firearm in violation of 18 U. S. C. § 922 (h). Prior to trial, respondent moved to suppress certain incriminating statements he had made to police officers and to agents of the Bureau of Alcohol, Tobacco, and Firearms. Over his objections, the District Court referred the motion to a Magistrate for an evidentiary hearing pursuant to the Federal Magistrates Act, 28 U. S. C. § 636 (b)(1)(B).
The evidence received at the suppression hearing disclosed that on August 8, 1976, two police officers responded to a report of a crime in progress. When they arrived at the scene, they observed respondent standing next to one Jimmy Bastón, who was lying on the street, bleeding from the head. Respondent was placed under arrest for illegal use of a weapon and was given Miranda warnings. The arresting officers testified that respondent explained at the time of his arrest and after the warning that he had been fighting with Bastón over a family dispute and had brought the gun with him in case any of Baston’s friends tried to interfere.
In due course, state charges were filed against respondent. One month later, on November 19, 1976, Agents Russell and McCulloch of the Bureau of Alcohol, Tobacco, and Firearms interviewed respondent at his home. According to their testimony at the suppression hearing, the agents had been informed by state officials that a state firearms charge was pending against respondent. The agents questioned respondent about the gun found in his possession at the time he was arrested because it had at one time been owned by an out-of-state man who had been slain in an unsolved homicide. At this interview, respondent gave a different version of the events, stating that he had seized the gun from Bastón during their August 8 fight and that he did not know where Bastón had obtained a gun. The agents asked respondent to help them locate Bastón and told him they would inform the United States Attorney of his cooperation if he were subsequently prosecuted.
Respondent’s testimony before the Magistrate concerning the November 19 interview varied from that of the federal agents. According to his testimony, he was informed that he would shortly be indicted for violations of federal firearms laws, but that if he agreed to cooperate, “somebody would talk to the prosecutor, and it would be dismissed.” He also testified that he was told that if he did not agree to help, he could find himself “going to the Federal penitentiary for a long time.”
On January 12, 1977, respondent telephoned the agents and requested a meeting. At this interview, he retracted his November 19 version and stated that he had not taken the gun from Bastón, but had obtained it from his half-brother. He testified at the suppression hearing that he made the incriminating statements at the January 12 meeting only after first obtaining confirmation from the agents of their November 19 promise that the indictment would be dismissed if he cooperated. The agents testified that no such promise was ever made to respondent, either on November 19 or on January 12. They testified that at the January 12 meeting respondent agreed to act as an informant and that they gave him $10 at that time to assist him in gathering information.
A final meeting occurred on January 14, 1977. Respondent returned to the local offices of the Bureau of Alcohol, Tobacco, and Firearms, accompanied by his wife and children. He was informed by Agent McCulloch that his case had been referred to the United States Attorney for prosecution. The agents again discussed with him the possibility of his becoming an informant, and repeated their promise that any cooperation would be brought to the attention of the United States Attorney. Agent McCulloch gave respondent $50 to pay expenses of acquiring information.
II
The focus of respondent’s legal argument at the suppression hearing was that under Malloy v. Hogan, 378 U. S. 1, 7 (1964), and Bram v. United States, 168 U. S. 532, 542-543 (1897), his confession was not freely and voluntarily given. He contended that he had been induced to utter the incriminating statements through a promise of immunity and sought to demonstrate a course of conduct on the part of the agents supportive of such a promise.
In his report and findings, the Magistrate recommended that the motion to suppress the statements made on August 8, November 19, and January 12 be denied. He made findings that respondent had knowingly, intelligently, and voluntarily made inculpatory statements on all three occasions. Moreover, the Magistrate specifically stated: “I find the testimony of the Alcohol, Tobacco and Firearms Agent more credible ... ; I find that Federal agents never advised [respondent] that charges against him would be dismissed, if he cooperated.” App. to Pet. for Cert. 41a. The evidence before the Magistrate showed that respondent had altered his version of events on several occasions.
Respondent filed objections to the Magistrate’s report. In rendering its decision, the District Court stated that it considered the transcript of the hearing before the Magistrate on the motion to suppress, the parties’ proposed findings of fact, conclusions of law, and supporting memoranda, and that it read the recommendation of the Magistrate and heard oral argument of counsel. Finding “that the three statements given by the defendant and sought to be suppressed were made voluntarily,” the District Court accepted the recommendation of the Magistrate and denied the motion to suppress.
By agreement of the parties, the court tried respondent on the basis of the transcript of the suppression hearing, and stipulations that the firearm had been manufactured in Florida and that respondent had been convicted of eight felonies. He was found guilty and sentenced to six months’ imprisonment to be followed by four and one-half years on probation.
The Court of Appeals reversed. 592 F. 2d 976. It first rejected the statutory arguments, holding that the District Court had the power to refer to a magistrate the motion to suppress and did not abuse its discretion under the statute in deciding the issue without hearing live testimony of disputed questions of fact. Turning to the constitutional issues, the court held that the referral provisions of the Federal Magistrates Act, 28 U. S. C. § 636 (b)(1)(B), did not violate Art. Ill of the Constitution because the statute required the District Court to make a de novo determination of any disputed portion of the Magistrate’s proposed findings and recommendations. However, the Court of Appeals held that respondent had been deprived of due process by the failure of the District Court personally to hear the controverted testimony. Where credibility is crucial to the outcome, “the district court cannot constitutionally exercise its discretion to refuse to hold a hearing on contested issues of fact in a criminal case.” 592 F. 2d, at 986. The District Court was directed to hold a new hearing.
Ill
We first address respondent’s contention that under the statute, the District Court was required to rehear the testimony on which the Magistrate based his findings and recommendations in order to make an independent evaluation of credibility. The relevant statutory provisions authorizing a district court to refer matters to a magistrate and establishing the mode of review of the magistrate’s actions are in 28 U. S. C. § 636 (b)(1). In § 636 (b) (1) (A), Congress provided that a district court judge could designate a magistrate to “hear and determine” any pretrial matter pending before the court, except certain “dispositive” motions. Review by the district court of the magistrate’s determination of these nondispositive motions is on a “clearly erroneous or contrary to law” standard.
Certain “dispositive” motions, including a “motion ... to suppress evidence in a criminal case,” are covered by § 636 (b)(1)(B). As to these “dispositive” motions, the district judge may “designate a magistrate to conduct hearings, including evidentiary hearings, and to submit to a judge of the court proposed findings of fact and recommendations for the disposition, by a judge of the court of [the] motion.” However, the magistrate has no authority to make a final and binding disposition. Within 10 days after the magistrate files his proposed findings and recommendations, any party may file objections. The statute then provides:
“A judge of the court shall make a de novo determination of those portions of the report or specified proposed findings or recommendations to which objection is made. A judge of the court may accept, reject, or modify, in whole or in part, the findings or recommendations made by the magistrate. The judge may also receive further evidence or recommit the matter to the magistrate with instructions.” § 636 (b)(1) (emphasis added).
It should be clear that on these dispositive motions, the statute calls for a de novo determination, not a de novo hearing. We find nothing in the legislative history of the statute to support the contention that the judge is required to rehear the contested testimony in order to carry out the statutory command to make the required “determination.” Congress enacted the present version of § 636 (b) as part of the 1976 amendments to the Federal Magistrates Act in response to this Court’s decision in Wingo v. Wedding, 418 U. S. 461 (1974). Wingo held that as a matter of statutory construction, the 1968 Magistrates Act did not authorize magistrates to hold evidentiary hearings in federal habeas corpus cases. Congress amended the Act “in order to clarify and further define the additional duties which may be assigned to a United States Magistrate in the discretion of a judge of the district court.” S. Rep. No. 94-625, p. 1 (1976) (hereinafter S. Rep.); H. R. Rep. No. 9A-1609, p. 2 (1976) (hereinafter H. R. Rep.).
The bill as reported out of the Senate Judiciary Committee did not include the language requiring the district court to make a de novo determination. Rather, it included only the language permitting • the district court to “accept, reject, or modify, in whole or in part, the findings or recommendations made by the magistrate.” Yet the Senate Report which accompanied the bill emphasized that the purpose of the bill’s language was to vest “ultimate adjudicatory power over dis-positive motions” in the district court while granting the “widest discretion” on how to treat the recommendations of the magistrate. S. Rep., at 10.
The House Judiciary Committee added to the Senate bill the present language of the statute, providing that the judge shall make a “de novo determination” of contested portions of the magistrate’s report upon objection by any party. According to the House Report, “[t]he amendment states expressly what the Senate implied: i. e. that the district judge in making the ultimate determination of the matter, would have to give fresh consideration to those issues to which specific objection has been made by a party.” The Report goes on to state, quite explicitly, what was intended by “de novo determination”:
“The use of the words ‘de novo determination’ is not intended to require the judge to actually conduct a new hearing on contested issues. Normally, the judge, on application, will consider the record which has been developed before the magistrate and make his own determination on the basis of that record, without being bound to adopt the findings and conclusions of the magistrate. In some specific instances, however, it may be necessary for the judge to modify or reject the findings of the magistrate, to take additional evidence, recall witnesses, or recommit the matter to the magistrate for further proceedings.” H. R. Rep., at 3.
Further evidence that Congress did not intend to require the district court to rehear the witnesses is provided in the House Committee Report’s express adoption of the Ninth Circuit’s procedures for district court review of a magistrate’s credibility recommendations as announced in Campbell v. United States District Court for the Northern District of California, 501 F. 2d 196, cert. denied, 419 U. S. 879 (1974). There, in language quoted in the Committee Report, the court had stated: “ Tf [the district court] finds there is a problem as to the credibility of a witness or witnesses or for other good reasons, it may, in the exercise of its discretion, call and hear the testimony of a witness or witnesses in an adversary proceeding. It is not required to hear any witness and not required to hold a de novo hearing of the case.’ ” H. R. Rep., at 3-4 (emphasis added), quoting 501 F. 2d, at 206.
Congressional intent, therefore, is unmistakable. Congress focused on the potential for Art. Ill constraints in permitting a magistrate to make decisions on dispositive motions. See S. Rep., at 6; H. R. Rep., at 8. The legislative history discloses that Congress purposefully used the word determination rather than hearing, believing that Art. Ill was satisfied if the ultimate adjudicatory determination was reserved to the district court judge. And, in providing for a “de novo determination” rather than de novo hearing, Congress intended to permit whatever reliance a district judge, in the exercise of sound judicial discretion, chose to place on a magistrate’s proposed findings and recommendations. See Mathews v. Weber, 423 U. S. 261, 275 (1976).
IV
Having rejected respondent’s statutory argument, we turn to his constitutional challenge. He contends that the review procedures established by § 636 (b)(1) permitting the district court judge to make a de novo determination of contested credibility assessments without personally hearing the live testimony, violate the Due Process Clause of the Fifth Amendment and Art. Ill of the United States Constitution.
A
The guarantees of due process call for a “hearing appropriate to the nature of the case.” Mullane v. Central Hanover Bank & Trust Co., 339 U. S. 306, 313 (1950). The issue before us, therefore, is whether the nature of the issues presented and the interests implicated in a motion to suppress evidence require that the district court judge must actually hear the challenged testimony. The core of respondent’s challenge to the statute is that “[t]he one who decides must hear.” Morgan v. United States, 298 U. S. 468, 481 (1936). Here, he contends, only the magistrate “hears,” but the district court is permitted to “decide” by reviewing the record compiled before the magistrate and making a final determination.
In Mathews v. Eldridge, 424 U. S. 319, 335 (1976), we emphasized that three factors should be considered in determining whether the flexible concepts of due process have been satisfied: (a) the private interests implicated; (b) the risk of an erroneous determination by reason of the process accorded and the probable value of added procedural safeguards; and (c) the public interest and administrative burdens, including costs that the additional procedures would involve. In providing the fullest measure of due process protection, the Court of Appeals stressed that in this particular case the success or failure of the motion to suppress would, as a practical matter, determine the outcome of the prosecution.
Of course, the resolution of a suppression motion can and often does determine the outcome of the case; this may be true of various pretrial motions. We have repeatedly pointed out, however, that the interests underlying a voluntariness hearing do not coincide with the criminal law objective of determining guilt or innocence. See, e. g., United States v. Janis, 428 U. S. 433, 453-454 (1976); United States v. Peltier, 422 U. S. 531, 535-536, 538-539 (1975); Rogers v. Richmond, 365 U. S. 534, 540-544 (1961). In Lego v. Twomey, 404 U. S. 477 (1972), we considered whether the prosecution was required to prove beyond a reasonable doubt that a confession was voluntary. In holding that a preponderance of the evidence was sufficient, we stated that “the purpose that a volun-tariness hearing is designed to serve has nothing whatever to do with improving the reliability of jury verdicts.” Id., at 486. Accord, Jackson v. Denno, 378 U. S. 368, 384-385 (1964), holding that the “reliability of a confession has nothing to do with its voluntariness.” A defendant who has not prevailed at the suppression hearing remains free to present evidence and argue to — and may persuade — the jury that the confession was not reliable and therefore should be disregarded. See 18 U. S. C. § 3501 (a).
This Court on other occasions has noted that the interests at stake in a suppression hearing are of a lesser magnitude than those in the criminal trial itself. At a suppression hearing, the court may rely on hearsay and other evidence, even though that evidence would not be admissible at trial. United States v. Matlock, 415 U. S. 164, 172-174 (1974); Brinegar v. United States, 338 U. S. 160, 172-174 (1949); Fed. Rules Evid. 104 (a), 1101 (d)(1). Furthermore, although the Due Process Clause has been held to require the Government to disclose the identity of an informant at trial, provided the identity is shown to be relevant and helpful to the defense, Roviaro v. United States, 353 U. S. 53, 60-61 (1957), it has never been held to require the disclosure of an informant’s identity at a suppression hearing. McCray v. Illinois, 386 U. S. 300 (1967). We conclude that the process due at a suppression hearing may be less demanding and elaborate than the protections accorded the defendant at the trial itself.
To be sure, courts must always be sensitive to the problems of making credibility determinations on the cold record. More than 100 years ago, Lord Coleridge stated the view of the Privy Council that a retrial should not be conducted by reading the notes of the witnesses’ prior testimony:
“The most careful note must often fail to convey the evidence fully in some of its most important elements.. .. It cannot give the look or manner of the witness: his hesitation, his doubts, his variations of language, his confidence or precipitancy, his calmness or consideration; . . . the dead body of the evidence, without its spirit; which is supplied, when given openly and orally, by the ear and eye of those who receive it.” Queen v. Bertrand, 4 Moo. P. C. N. S. 460, 481, 16 Eng. Rep. 391, 399 (1867).
This admonition was made with reference to an appellate court’s review of a nisi prius judge in a trial on the merits; here we are dealing with a situation more comparable to a special master’s findings or actions of an administrative tribunal on findings of a hearing officer.
The Court of Appeals rejected an analogy to administrative agency cases because of its view that the interest inherent in a suppression motion was often the equivalent, as a practical matter, of the trial itself. Our view of the due process demands of a motion to suppress evidence makes those agency cases relevant, although to be sure we do not suggest that the interests inherent in administrative adjudications are always equivalent to those implicated in a constitutional challenge to the admissibility of evidence in a criminal case. Generally, the ultimate factfinder in administrative proceedings is a commission or board, and such trier has not heard the witnesses testify. See, e. g., 5 U. S. C. § 557 (general rule under the Administrative Procedure Act); 29 U. S. C. § 160 (c) (National Labor Relations Board); 33 U. S. C. § 921 (b)(3) (Benefits Review Board); 17 CFR § 207.17 (g)(2) (1979) (Securities and Exchange Commission). While the commission or board — or an administrator- — may defer to the findings of a hearing officer, that is not compelled. See, e. g., Universal Camera Corp. v. NLRB, 340 U. S. 474 (1951); NLRB v. Mackay Radio & Tel. Co., 304 U. S. 333, 350-351 (1938); Morgan v. United States, 298 U. S. 468 (1936); Utica Mutual Ins. Co. v. Vincent, 375 F. 2d 129, 132 (CA2) (Friendly, J.), cert. denied, 389 U. S. 839 (1967).
We conclude that the due process rights claimed here are adequately protected by § 636 (b)(1). While the district court judge alone acts as the ultimate decisionmaker, the statute grants the judge the broad discretion to accept, reject, or modify the magistrate’s proposed findings. That broad discretion includes hearing the witnesses live to resolve conflicting credibility claims. Finally, we conclude that the statutory scheme includes sufficient procedures to alert the district court whether to exercise its discretion to conduct a hearing and view the witnesses itself.
B
In passing the 1976 amendments to the Federal Magistrates Act, Congress was alert to Art. Ill values concerning the vesting of decisionmaking power in magistrates. Accordingly, Congress made clear that the district court has plenary discretion whether to authorize a magistrate to hold an eviden-tiary hearing and that the magistrate acts subsidiary to and only in aid of the district court. Thereafter, the entire process takes place under the district court’s total control and jurisdiction.
We need not decide whether, as suggested by the Government, Congress could constitutionally have delegated the task of rendering a final decision on a suppression motion to a non-Art. Ill officer. See Palmore v. United States, 411 U. S. 389 (1973). Congress has not sought to make any such delegation. Rather, Congress has provided that the magistrate’s proposed findings and recommendations shall be subjected to a de novo determination “by the judge who . . . then exercise [s] the ultimate authority to issue an appropriate order.” S. Rep., at 3. Moreover, “[t]he authority — and the responsibility — to make an informed, final determination ... remains with the judge.” Mathews v. Weber, 423 U. S., at 271.
On his Art. III claim, Crowell v. Benson, 285 U. S. 22 (1932), and its progeny offer little comfort to respondent. There, the Court stated that “[i]n cases brought to enforce constitutional rights, the judicial power of the United States necessarily extends to the independent determination of all questions, both of fact and law, necessary to the performance of that supreme function.” Id., at 60. See also Ng Fung Ho v. White, 259 U. S. 276 (1922). While stating that “the enforcement of constitutional rights requires that the Federal court should determine such an issue upon its own record and the facts elicited before it,” 285 U. S., at 64, the Court pointedly noted a “distinction of controlling importance” between records formed before administrative agencies and those compiled by officers of the court such as masters in chancery or commissioners in admiralty where the proceeding is “constantly subject to the court’s control.” We view the statutory scheme here as rendering a magistrate’s recommendations more analogous to a master or a commissioner than to an administrative agency for Art. Ill purposes.
Moreover, four years later, in St. Joseph Stock Yards Co. v. United States, 298 U. S. 38 (1936), Mr. Chief Justice Hughes substantially cut back on the Court’s Crowell holding, which he had authored, and on which respondent relies. The question there was whether administrative rate regulations were unconstitutionally confiscatory. While reaffirming his statement that administrative agencies cannot finally determine “constitutional facts,” Mr. Chief Justice Hughes noted:
“But this judicial duty to exercise an independent judgment does not require or justify disregard of the weight which may properly attach to findings [by an administrative body] upon hearing and evidence. On the contrary, the judicial duty is performed in the light of the proceedings already had and may be greatly facilitated by the assembling and analysis of the facts in the course of the legislative determination.” 298 U. S., at 53.
See also Estep v. United States, 327 U. S. 114, 122-123 (1946). Thus, although the statute permits the district court to give to the magistrate’s proposed findings of fact and recommendations “such weight as [their] merit commands and the sound discretion of the judge warrants,” Mathews v. Weber, supra, at 275, that delegation does not violate Art. Ill so long as the ultimate decision is made by the district court.
We conclude that the statute strikes the proper balance between the demands of due process and the constraints of Art. III. Accordingly, the judgment of the Court of Appeals is
Reversed.
Before the Court of Appeals, respondent apparently conceded that the statute permits the procedures employed here. His statutory arguments in the Court of Appeals were that the reference was invalid because not made pursuant to required enabling rules and that the Court of Appeals should exercise its supervisory powers to prohibit the procedure employed. That court rejected both arguments, and he has pursued neither before this Court.
As originally introduced in the Senate, the bill provided that upon request by a party to a proceeding before a magistrate, the district “court shall hear de novo those portions of the report or specific proposed findings of fact or conclusions of law to which objection is made.” S. 1283, 94th Cong., 1st Sess. (1975) (emphasis added). As reported out of the Senate Judiciary Committee, however, this language, including the word “hear,” was deleted.
We conclude that to construe §636 (b)(1) to require the district court to conduct a second hearing whenever either party objected to the magistrate’s credibility findings would largely frustrate the plain objective of Congress to alleviate the increasing congestion of litigation in the district courts. We cannot “impute to Congress a purpose to paralyze with one hand what it sought to promote with the other.” Clark v. Uebersee Finanz-Korporation, 332 U. S. 480, 489 (1947).
Under the Fifth Amendment, a criminal defendant may not be compelled to testify against himself. In that sense, the exclusion of involuntary confessions derives from the Amendment itself. United States v. Janis, 428 U. S. 433, 443 (1976).
Lego v. Twomey, 404 U. S. 477 (1972), also rejected the argument that because of the high value society places on the constitutional right to be free from compulsory self-incrimination, due process requires proof of voluntariness beyond a reasonable doubt. This Court found no indication that federal rights would suffer from determining admissibility by a preponderance of the evidence.
Nothing in the Magistrates Act or other statute precludes renewal at trial of a motion to suppress evidence even though such motion was denied before trial. A district court's authority to consider anew a suppression motion previously denied is within its sound judicial discretion. See generally Gouled v. United States, 255 U. S. 298, 312 (1921); Rouse v. United States, 123 U. S. App. D. C. 348, 359 F. 2d 1014 (1966).
Neither the statute nor its legislative history reveals any specific consideration of the situation where a district judge after reviewing the record in the process of making a de novo “determination” has doubts concerning the credibility findings of the magistrate. The issue is not before us, but we assume it is unlikely that a district judge would reject a magistrate’s proposed findings on credibility when those findings are dispositive and substitute the judge’s own appraisal; to do so without seeing and hearing the witness or witnesses whose credibility is in question could well give rise to serious questions which we do not reach.
The Committee Reports noted several instances prior to the 1976 amendments where Congress had vested in officers of the court, other than the judge, the power to exercise discretion in performing an adjudicatory function, “subject always to ultimate review by a judge of the court,” citing 11 U. S. C. § 67 (c) (reference to bankruptcy referee) and 28 U. S. C. § 1920 (power of clerk of court to tax costs). By analogy, Congress reasoned that permitting the exercise of an adjudicatory function by a magistrate, subject to ultimate review by the district court, would also pass constitutional muster. S. Rep., at 6; H. R. Rep., at 8.
In Crowell, in reviewing the constitutionality of the delegation of fact-finding to administrative officers to consider claims under the Longshoremen’s and Harbor Workers’ Compensation Act, the Court was concerned that Congress could not reach beyond the constitutional limits which are inherent in the admiralty and maritime jurisdiction. It stated that unless the injuries to which the Act relates occurred upon the navigable waters of the United States, they would fall outside that jurisdiction. 285 U. S., at 55.
The Crowell Court rejected a wholesale attack on any delegation of factfinding to the administrative tribunal. It noted that “there is no requirement that, in order to maintain the essential attributes of the judicial power, all determinations of fact in constitutional courts shall be made by judges.” Id., at 51-52.
In exercising our original jurisdiction under Art. Ill, we appoint special masters who may be either 'Art. Ill judges or members of the Bar; the role of the master is, for these purposes, analogous to that of a magistrate. The master is generally charged to “take such evidence as may be . . . necessary,” Nebraska v. Iowa, 379 U. S. 996 (1965), and to “find the facts specially and state separately his conclusions of law thereon.” Mississippi v. Louisiana, 346 U. S. 862 (1953). In original cases, as under the Federal Magistrates Act, the master’s recommendations are advisory only, yet this Court regularly acts on the basis of the master’s report and exceptions thereto.