What is the test for producing in camera review of a prosecution law enforcement witness file?

Those concerns have been addressed and rejected by our recent decision in United States v. Henthorn, 931 F.2d 29 (9th Cir.1991), application for cert. pending, No. 91-6160. There, the district court refused to order the government to produce for in camera review the personnel files of all prosecution law enforcement witnesses. We reversed on appeal, rejecting the government's argument that the defendant should be required to make an initial showing of materiality. We concluded that "the government has a duty to examine personnel files upon a defendant's request for their production." Id.