The United States government operates under a system of checks and balances between the three branches. Acts passed by Congress and signed into law by the President can be declared unconstitutional by the Supreme Court, part of the third branch of government, the Judicial. The President's nominations of Cabinet members and other officers of the United States having to be approved by the Senate is another example. Their are things that one branch can completely control, things the other branches can control along with it, and things that one branch has no control over. This system is in place to prevent one branch from gaining to much power over the others.