Sorry I hope this doesn’t go against the no politics rule. I promise this isn’t meant to be partisan but rather questions on legality for purely curiosity sake. But if it is please remove and I understand.

Is there a limit to US presidential power when it comes to pardons? Can it be used for any crime in the US or are there some things it cannot?

For example, if someone were to hypothetically carry out an assassination on a sitting president (any president, this is just a thought exercise), they would be sentenced to death most likely. But let’s say that the person was hired by the sitting VP. Assassin takes out the president, VP becomes president, then pardons assassin.

Based on current laws, could that happen? What other bizarre uses could happen?

Please keep this non-political per the rules.