The common interest doctrine can sometimes protect communications among separately represented clients who share an identical legal interest in litigation or anticipated litigation. But that doctrine is not a separate legal protection.
In Babygrande Global, Inc. v. Rodriguez, defendants sought to seal an email “which they assert is privileged under a joint defense privilege,” another name for the common interest doctrine. No. 24-CV-6785 (JGLC), 2025 U.S. Dist. LEXIS 264275, at *1 (S.D.N.Y. Dec. 22, 2025). The court denied the motion to seal, noting that “[a]lthough [the email] was sent at a time when the joint defense privilege applied, . . . it was never privileged to begin with.” Id. at *3.
The common interest doctrine can be an important source of protection, but lawyers should remember that it does not create a protection from discovery — it can sometimes prevent the waiver of an existing protection.