Limited Government: We have a bill of rights
Separation of Powers: Supreme court, President, and Congress
Checks and Balances: The president can veto stuff from congress and congress can override the veto with 2/3 vote. Supreme court can declare things unconstitutional.
Judicial Review: Supreme court can declare things unconstitutional.
Federalism: the theory or advocacy of federal principles for dividing powers between member units and common institutions.
I hope that this is the answer that you were looking for and it has helped you.