A decision last week from the U.S. District Court for the Southern District of Florida, United States v. Vuteff, illustrates a benefit of utilizing a written joint defense agreement properly tailored to limit future conflicts, rather than relying on the oral agreements that are common among many practitioners.

The court in Vuteff disqualified a lawyer whose former client was in an oral joint defense agreement with another individual who later “flipped” to cooperate with the government. It held that the agreement imposed a duty of confidentiality on the lawyer, which would be violated by the lawyer’s use of information obtained through the joint defense to attack the cooperator’s credibility.