What power would that be? The President doesn't make laws, nor does he rule on their Constitutionality. He could issue a pardon, but she hasn't comitted a crime. This is Civics 101.
Good try. I already layed that out didn't I? Congress may still do it but the President can do what it won't and protect a federal witness subpoened by the U.S. Congress. Bubba got a court order can't "W"?