Must “Common Interest” Agreements be in Writing?

July 2, 2003

The “common interest” doctrine sometimes allows parties to share privileged documents without waiving the protection—as long as they share a common legal interest and the sharing furthers that interest. Must the parties memorialize their agreement in writing?

In SR International Business Insurance Co. v. World Trade Center Properties LLC, No. 01 Civ. 9291 (JSM), 2003 U.S. Dist. LEXIS 1106, at *2 (S.D.N.Y. Jan 29, 2003), the court ultimately found that communication among clients did not deserve common interest protection, but explained that the absence of a written common interest agreement “would not, in itself, defeat this privilege.”

Although clients and lawyers must establish a number of prerequisites to earn protection under the “common interest” doctrine, in most courts a written agreement is not one of those prerequisites.