What is the standard for in camera review to determine the applicability of the crime-fraud exception?

We think that the following standard strikes the correct balance. Before engaging in in camera review to determine the applicability of the crime-fraud exception, "the judge should require a showing of a factual basis adequate to support a good faith belief by a reasonable person," Caldwell v. District Court, 644 P.2d 26, 33 (Colo.1982), that in camera review of the materials may reveal evidence to establish the claim that the crime fraud exception applies.

491 U.S. at 572, 109 S.Ct. at 2631.