The United States Constitution separates the federal government into the legislative, executive and judicial branches. The legislative branch, also known as Congress, makes federal laws. The executive branch enforces the laws. The judicial branch interprets and applies the laws.
Each branch of government limits the power of the other two branches. The Supreme Court can overturn congressional legislation or executive orders by deeming these acts unconstitutional. The president appoints justices to the Supreme Court, but Congress must confirm these appointments. Congress must also confirm the president's cabinet appointments. The president can veto a congressional act, as well, preventing it from becoming a law. For Congress to override a presidential veto, there must be a two-thirds majority vote in both the Senate and House of Representatives.