"The President ... shall have Power to grant Reprieves and Pardons for Offenses against the United States, except in Cases of impeachment" [1]. Everything after that is, at best, case law.
> [1] The pardon would have put Nixon in a difficult position on the witness stand since he would not have been able to assert any Fifth Amendment privilege when questioned about his actions as president.
No.
"The President ... shall have Power to grant Reprieves and Pardons for Offenses against the United States, except in Cases of impeachment" [1]. Everything after that is, at best, case law.
[1] https://en.wikipedia.org/wiki/Federal_pardons_in_the_United_...