The framers of the Constitution intended Congress to be the preeminent branch of government, sitting at the center of national power. As a result, Congress wields significant but limited power.

Powers Granted by the Constitution

The Constitution enumerates some powers that Congress has but also specifies some powers that Congress does not have.


Enumerated powers, or the expressed powers, are powers the Constitution explicitly grants to Congress, including the power to declare war and levy taxes.

Implied Powers

Article I, Section 8, of the Constitution also contains the necessary and proper clause, or the elastic clause, which gives Congress extra powers. As interpreted by the Supreme Court in McCulloch v. Maryland (1819), this clause means that Congress can assume other powers and pass laws in order to fulfill its duties. The powers granted by the necessary and proper clause are called implied powers.

Limits on Congress

Article I, Section 9, of the Constitution places three important limits on Congress and its powers. Congress cannot

  • pass ex post facto laws, which outlaw acts after they have already been committed.
  • pass bills of attainder, which punish individuals outside of the court system.
  • suspend the writ of habeas corpus, a court order requiring the federal government to charge individuals arrested for crimes. Congress can only suspend the writ of habeas corpus during times of national emergency.

Power in a Bicameral Legislature

The House of Representatives and the Senate must jointly decide to exercise most of the powers granted to Congress. When Congress declares war, for example, both houses must pass the exact same declaration. Similarly, both houses must pass identical versions of the same law before the law can take effect. There are some exceptions, however, in which the House and the Senate wield power alone.

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