Federal common law governs federal question case privilege issues. Federal courts sitting in diversity should look to their host jurisdiction’s choice of law rules when deciding which state’s privilege law applies. But what about privilege issues involved in pendent state law claims in federal question cases?

In Williams & Cochrane, LLP v. Rosette, the court conceded “federal courts have split in their approach.” Case No. 17cv1436-GPC-DEB, 2020 U.S. Dist. LEXIS 109750, at *11 (S.D. Cal. June 23, 2020). First, “[a] majority of federal courts have applied federal privilege law to claims of privilege in federal question actions with pendent state law claims.” Id. Second, some courts “have held that both federal and state privilege law should apply in a federal question action with pendent state claims.” Id. Third, “[s]till others have applied state privilege law in federal question actions with pendent state claims where the predominant nature of all the claims are based on state law.” Id. at *12. The court linguistically threw up its hands, noting that “frankly, the law in this context is unclear and courts have adopted a multiplicity of approaches.” Id. at *13. The court ultimately concluded that the magistrate judge had not erred in applying California privilege law – “given that this litigation is mostly centered on California based contract claims.” Id. at *13-14.

Although this state law pendent claim privilege issue may arise only rarely, courts’ surprising lack of consensus highlights lawyers’ obligation to first conduct a privilege choice of law analysis.