under 19 U.S.C. § 1508, in order to ensure compliance with the Customs laws. The records were needed for a proper determination of the possible civil and criminal liability of Modes. Appellants obtained an extension of time to comply with the summonses so that Wilson and Tim Millis, his investigator, could travel to the Far East to secure evidence from business associates.
Upon returning from abroad to Dallas/Fort Worth International Airport, Mil-lis was carrying in his briefcase Wilson’s legal files pertaining to Customs’s investigation of Modes. When Millis passed through Customs’s checkpoint, an agent searched the briefcase containing the files and took them, refusing to return them to Millis or Wilson despite their protests. No reason was given for the seizure. The files were returned by Customs two days later, but because Millis had not been allowed to make an inventory prior to their being taken, he was unable to determine whether any of the documents had been removed and of course had no way of knowing whether they had been photocopied.
Subsequently, Wallace issued and served two new summonses on Modes and Wilson, identical to the first two except that the time period for the records sought differed somewhat, i.e., 10/83 — 1/85 rather than 1/83 — 1/85. Appellants met with Wallace as required by the later summonses but, based upon the attorney-client privilege and the fifth amendment right against self-incrimination, refused to produce documents.
Wallace and the government filed in district court a petition to enforce the summonses, pursuant to 19 U.S.C. § 1510. That court, pursuant to 28 U.S.C. § 636(b)(1), referred the petition to a magistrate “for disposition.” After a hearing, the magistrate issued findings and recommendations, concluding that the summonses should be enforced. The district court entered an order adopting the magistrate’s findings and recommendations after considering Modes and Wilson’s objections. That order was stayed pending this appeal.
II. Standard, of Review Applied by District Court.
Under the plain language of 28 U.S. C. § 636(b)(1), Fed.R.Civ.P. 72(b), and all of the relevant cases, a district court must engage in de novo review where a party has objected to a magistrate’s decision. However, the district judge in this case announced that he was applying the “clearly erroneous, abuse of discretion and contrary to law” standard of review, which is appropriate only where there has been no objection to the magistrate’s ruling. The only dispute is whether the district judge actually engaged in de novo review despite announcing an improper standard. If he did not, we must remand.
The government cites authorities to the effect that a court may be found to have reviewed a magistrate’s decision de novo even if it uses pro forma language indicative of a different standard. “[I]n 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.” United States v. Raddatz, 447 U.S. 667, 676, 100 S.Ct. 2406, 2412, 65 L.Ed.2d 424 (1980). Accord, Aluminum Co. of Am. v. E.P.A., 663 F.2d 499, 502 (4th Cir.1981) (use of “clearly erroneous” in district court’s opinion does not preclude possibility that de novo review occurred).
The government’s reliance upon these cases is misplaced. Raddatz’s distinction between a de novo hearing and de novo review does not really help the government, as Modes does not argue that a hearing should have occurred but only that the district court obviously did not engage in de novo review. Furthermore, the language concerning the “clearly erroneous” term in Aluminum Co. is dictum: The Fourth Circuit proceeded to find that de novo review had not occurred in that case, even though the district court patently had engaged in more extensive review than occurred here. Thus, that court, although de-emphasizing the significance of labels, ultimately held that “the district judge did