A federal appeals court is due to consider next week a case that could decide just how far prosecutors can go to pierce a corporate executive’s attorney-client privilege.

Both sides have filed their briefs in the case, in which federal prosecutors used the company’s outside counsel to testify against and convict Ian Norris, then-CEO of the Morgan Crucible Co. in the U.K. The company was accused of price-fixing on carbon products, such as brushes used in electric motors.