What is the test for making a prima facie showing that communications were in furtherance of a crime de novo or for abuse of power?

Whether we review a district court's conclusion that the government has made a prima facie showing that communications were made in furtherance of a crime de novo or for an abuse of discretion appears to be an open question in this circuit. United States v. Laurins, 857 F.2d 529, 541 (9th Cir.1988), cert. denied, 492 U.S. 906, 109 S.Ct. 3215, 106 L.Ed.2d 565 (1989). We need not resolve it, however, because under either standard, we conclude that the government has met its burden.