concurring in part and dissenting in part.
I agree with the Court’s interpretation of the Federal Magistrates Act in Part III of its opinion. The terms and legislative record of § 636 (b)(1) plainly indicate that Congress intended to vest broad discretion in the district courts to decide whether or not to rehear witnesses already heard by a magistrate in a suppression proceeding.
The Court recognizes that “serious questions” would be raised if a district judge rejected a magistrate’s proposed findings on credibility. See ante, at 681, n. 7. But the Court finds no error in this case, where the District Court accepted the Magistrate’s judgment on credibility. I would reach a different conclusion. Under the standards set out in Mathews v. Eldridge, 424 U. S. 319, 335 (1976), due process requires a district court to rehear crucial witnesses when, as in this case, a suppression hearing turns only on credibility. As Mr. Justice Marshall points out in his dissenting opinion, *687the private interests at stake in a suppression hearing often are substantial. Moreover, the risk of erroneous deprivation of rights is real when a decider of fact has not heard and observed the crucial witnesses. The value of hearing and seeing those witnesses testify is undeniable. Finally, the government interest in limiting rehearing is not sufficient to outweigh these considerations.
In sum, I agree with Mr. Justice Marshall’s statement that, under the Due Process Clause of the Fifth Amendment, a hearing requirement should be imposed
“only in situations in which the case turns on issues of credibility that cannot be resolved on the basis of a record. ... If the district judge offered a statement of reasons presenting his independent view of the facts and explaining in some reasoned manner why it was not necessary for him to hear the witnesses in order to adopt that view, it would be an exceptionally rare case in which an abuse of discretion should be found.” Post, at 701-702.*
I would affirm the judgment of the Court of Appeals on this ground.
The classic situation requiring a hearing de novo is when the record of a suppression proceeding contains little beyond a “swearing contest.” In many cases, however, the entire record will contain additional evidence — direct or circumstantial — that fully supports the magistrate’s recommendation. In those cases, the district court may decide, within its sound discretion, not to hear witnesses.