It is a given that if Donald Trump is elected president, he will either have all federal charges against himself dropped, or if it is too late for that, just pardon himself. After all, Art. 1 Sec. 2 contains the text "... and he shall have Power to grant Reprieves and Pardons for Offences against the United States, except in Cases of Impeachment." There is no asterisk with a footnote explaining "except." So, the only exception is impeachment. Seems simple, no?
Maybe not. This article points out that maybe it isn't so easy for Trump. In Burdick v. United States, in 1915 the Supreme Court ruled that President Woodrow Wilson could not pardon a newspaper editor in order to eliminate his Fifth Amendment right not to testify before a grand jury. More generally, when two sections of the Constitution are in conflict, the courts can determine which one has priority. For example, Congress has the power to regulate interstate commerce. Would a law that made it a crime for The New York Times to mail the paper across state lines be considered constitutional based on the commerce clause? Probably not, because that would be in conflict with the First Amendment and most likely the First Amendment would win.
The Supreme Court has ruled in the past that the president has the "power to commute sentences on conditions which do not in themselves offend the Constitution." What kinds of conditions does the Constitution de facto place on the president's use of the pardon power? Perhaps these four:
If Trump were to pardon himself, that would run afoul of his oath to faithfully execute the law. The Supreme Court has repeatedly held that "no man can be a judge in his own case." When Richard Nixon was contemplating a self-pardon during the Watergate crisis, his own Justice Department invoked this principle to shut it down. In fact, the first article of impeachment against Nixon accused him of suborning perjury by dangling pardons in front of people he wanted to keep quiet.
These arguments may not stop Trump from trying it, but if he does, the case would end up in the Supreme Court. An issue would be who would have the standing to sue, but the case could get that far and then the Court would have to address both the standing issue and the self-pardon issue. (V)