President enforces laws via diplomacy, military force, and yada, yada. The supreme court interprets the law. The Congress makes the law. They have certain oversight abilities over one another, like the President can't ignore congress' laws, President can veto, Supreme court can declare things against the constitution.
The President is a very important politically due to traditional upgrades of the power of the president because of people like FDR, Theodore Roosevelt, Lincoln, but at the barest definition of the law, President is ONLY the head diplomat and head of the military. His political power comes from the tradition and prestige of the position, a little from his vetos. Though some, like Thomas Jefferson didn't believe in vetos so they never used it. Otherwise he's relatively powerless. I know that Trail of Tears was caused by Jackson ignoring that the Supreme Court ordered him to protect the Cherokee and he said no, letting Georgia do what it wanted. That's really only case where the power of the President was directly under his jurisdiction I know of off hand.
Though I think Lt. Fred hates America... sooo.