With a plea deal announced Friday in the second trial of former Trump campaign manager Paul Manafort, the possibility that President Trump will issue a pardon to prevent Manafort’s future cooperation with special counsel Robert S. Mueller III warrants fresh attention.

Trump’s supportive tweet about Manafort after his conviction in August on eight felony fraud counts, praising him for not cooperating with prosecutors, was widely interpreted as a hint of future presidential leniency. Trump has insisted on his “absolute” power to pardon even himself, and his lawyers in a secret January memo to Mueller asserted the president’s complete control over federal investigations as the nation’s chief law enforcement officer.

Trump and his team have tried to lay the groundwork for pardons to protect him from criminal charges. But can he use the pardon power in that way? Not in our reading of the law. A self-pardon, or a pardon that is self-protective and serves the same purpose as a self-pardon, would be an abuse of power that violates the Constitution and, as such, could warrant impeachment.