Can a president pardon himself? Four days before Richard Nixon resigned, his own Justice Department’s Office of Legal Counsel opined no, citing “the fundamental rule that no one may be a judge in his own case.” We agree.

The Justice Department was right that guidance could be found in the enduring principles that no one can be both the judge and the defendant in the same matter, and that no one is above the law.

The Constitution specifically bars the president from using the pardon power to prevent his own impeachment and removal. It adds that any official removed through impeachment remains fully subject to criminal prosecution. That provision would make no sense if the president could pardon himself.

https://www.washingtonpost.com/opinions/no-trump-cant-pardon-himself-the-constitution-tells-us-so/2017/07/21/f3445d74-6e49-11e7-b9e2-2056e768a7e5_story.html?utm_term=.50b7ae5de6b0