The subpoena was issued by the special committee investigating the Jan. 6 Capitol riot, and there are no doubt some partisan motives at play. Speaker Nancy Pelosi hopes the committee will find evidence to back up her claim that the riot was part of a larger plot to stage an “insurrection.” If so, it was the dumbest coup attempt in history, but the committee wants to ask Mr. Bannon about his role.

Mr. Bannon’s claim of executive privilege has no legal merit. The Supreme Court has said the privilege applies to conversations with a President performing the responsibilities of his office or making policy or decisions. Mr. Bannon left the White House staff in the summer of 2017. He has no immunity as a private citizen who may have spoken with then President Trump…

Mr. Bannon has a Fifth Amendment right not to incriminate himself if he does testify. But he doesn’t have the right to defy a subpoena with impunity. President Biden blundered when he interfered with a prosecutorial decision by saying publicly that Justice should prosecute Mr. Bannon. Mr. Biden has since admitted his mistake.