One way the constitution limits the powers of the federal government is through the separation of powers.
The government is divided in three branches: the executive power, invested in the President, the legislative power, given to Congress (the House of Representatives and the Senate), and the judicial power, vested in one Supreme Court and other federal courts.
The constitution establishes a system of checks and balances that ensures that separate branches are empowered to prevent actions by other branches and induce them to share power.
The system of checks and balances can be clearly seen, for example, in the creation of new laws:
Even though the legislative branch is the part of the government that makes the laws, the president has the power to veto said law. And, at the same time, the judicial branch can deem certain laws unconstitutional.
