Because if you assault me on the street and chop off one of my legs, and then it turns out that that leg had cancer, I would still expect you to go to jail. Wh

Because if you assault me on the street and chop off one of my legs, and then it turns out that that leg had cancer, I would still expect you to go to jail. What he did was illegal, which is why he needs a pardon to begin with (if not to signal that he has political support in case of an attack from other gov branch).