Second, whatever Team Trump may assert, the conversations between some combination of Manafort, Trump and the lawyers for both of them were not privileged, and Mueller is entitled to know their contents.

Defendants are entitled to enter into privileged conversations with their own lawyers, and the government cannot force the attorney to reveal them. This is entirely proper and part of the constitutional guarantee of effective assistance of counsel. A corollary to this principle permits co-defendants and potential defendants to share certain information — essentially the same information that would be shielded by the attorney-client privilege for either of them — on the grounds that they have a “common interest.” This interest is generally set out in a joint defense agreement, or JDA, which confirms the umbrella of covered discussions.

Crucially, however, the JDA can operate only among parties who , in fact, have a common interest. A defendant cannot simply pick and choose people he wants to talk to and thereafter claim that a conversation is privileged. And when Manafort entered into the cooperation agreement with the government, he ceased to have a common interest with other defendants, including the president, as a matter of law. As former U.S. attorney Chuck Rosenberg put it, having signed with the Yankees, he couldn’t give scouting reports to the Red Sox.