If the President does not agree with a law, it is his or her responsibility as chief executive to ensure the law is followed.
Step-by-step explanation:
In a federal, bicameral government working with three different agencies of power, functioning simultaneously in order to keep a check on each other's powers, there are possibilities of disagreement on decisions amongst the three agencies.
When a law that is not reasonable in the eyes of the President is passed by the Congress, the Constitution of the United States expects the President to leave no lag in the implementation of the law, despite the law not having his consent.