veto
The President checks the power of the Supreme Court by appointing Supreme Court justices and the Chief Justice (subject to Senate confirmation).
legilslative branch
The Supreme Court can check the power of Congress by ruling legislation passed by Congress is unconstitutional. The Supreme Court can do this when they a presented with an opportunity to hear a case which disputes a law. The supreme court's decision is final because it is the highest court in America.
The U.S. Supreme Court has the power to declare an act of Congress unconstitutional.
The supreme court can make sure the president doesn't abuse his power by deeming laws bills passed by the president unconstitutional.
veto
Congress can check the power of the Supreme Court by introducing amendments to the Constitution.
Courts can judge legislative acts to be unconstitutional. This means that the Supreme Court can say that a law that the Senate has passed is unconstitutional.
veto
federal spending
They help prevent presidents from becoming dictators.
The Congress and the Supreme Court provide a constitutional check on the President's powers