What is the federal district court's duty to review a report of a magistrate judge?

The district court's duties in connection with a Report of a magistrate judge are set forth in Federal Rule of Civil Procedure 72(b) and 28 U.S.C. 636(b). The district judge must "make a de novo determination of those portions of the report . . . to which objection is made," and "may accept, reject, or modify, in whole or in part, the findings or recommendations made by the magistrate." 28 U.S.C. 636(b). The district court need not review de novo those portions of a Report to which neither party objects. See United States v. Reyna-Tapia, 328 F.3d 1114, 1121-22 (9th Cir. 2003) (en banc). When

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