Congress exercises enumerated legislative powers granted principally in Article I. The president and federal courts likewise exercise powers conferred and bounded by Articles II and III, valid statutes, and the rest of the Constitution, but their authority is not described through an identical list of congressional powers. States possess broader general governing authority, often called the police power, yet they too are limited by the federal Constitution, valid federal law, and their own constitutions. Rights provisions restrict how otherwise valid power may be exercised. Structural rules also limit power by dividing responsibilities among branches and between national and state governments, although separation of powers and federalism remain distinct concepts with their own functions.

Limits are maintained by more than one institution. Courts may refuse to enforce unconstitutional action in cases within their jurisdiction. Legislators and executive officers take constitutional oaths and must assess the legality of their own actions. Bicameralism, vetoes, appointments, oversight, elections, impeachment, federalism, a free press, and organized opposition can expose or obstruct abuse. None is a perfect safeguard. A written prohibition is ineffective if every institution ignores it, while political resistance without a legal foundation does not by itself prove that an official lacks authority. Limited government depends on legal rules, institutions willing to enforce them, and citizens capable of recognizing when a policy dispute has become a question of unlawful power.

In a scenario, identify the claimed grant of authority and the alleged boundary. A question asking whether Congress has power to regulate an activity concerns a grant. A question asking whether an authorized regulation violates protected speech concerns a prohibition on the use of power. A legislature may therefore have power over a subject yet choose a constitutionally forbidden method, or it may pursue a sensible goal without possessing the required authority. Do not confuse limited government with popular sovereignty: the latter identifies the people as the ultimate source of legitimate authority, while the former asks how far the institutions they authorize may go. Nor does a policy become constitutional merely because it is popular or was enacted by elected representatives.

Video lesson: Natural rights, social contract, democracy, republicanism and limited government