It’s one thing to pardon a criminal out of a sense of mercy or on the belief that he has paid his debt to society.
It’s trickier when the president pardons someone who violated the law in pursuit of governmental policy, the way George H.W. Bush pardoned Iran-Contra participants, including Caspar Weinberger and five others.
But it would be an altogether different matter if Trump pardoned Arpaio for willfully refusing to follow the Constitution and violating the rights of people inside the U.S.
Impeachment is the only constitutional remedy for dealing with a president, writes Feldman, "who abuses the pardon power to break the system itself."