A federal appellate court in Wash­ington has waded into a closely watched dispute that has cast into question the confidentiality of corporate communications with in-house lawyers.

A three-judge panel of the U.S. Court of Appeals for the D.C. Circuit on May 7 heard from lawyers for Kellogg Brown & Root Services Inc. and a whistleblower in their battle over a trial judge’s order compelling the company to disclose certain documents.