Article One of the United States Constitution established the legislative branch of the federal government. Called the "People's Branch" because it embodies the people, Congress is divided into two chambers -- the House of Representatives and the Senate. The Constitution specifies the powers of the national legislature and those of the judicial and executive branches. According to the 10th Amendment, all powers not specifically granted to Congress by the Constitution belong to the states and the people.

Enumerated Powers

Section 3 of Article I gives the Senate sole power to try all impeachments, while Section 7 grants power over all federal spending to the House of Representatives. Section 8 specifies most powers of Congress as a whole. These powers include raising, making and borrowing revenue while punishing counterfeiters and making bankruptcy and naturalization laws. Congress has the power to establish post offices, is the protector of intellectual property rights, establishes courts and punishes both treason and piracy. Only Congress can declare war, raise armies and navies and suppress insurrections. It also has sole legislative authority over the District of Columbia and all federal facilities. These are the so-called enumerated, or expressed powers of Congress. Two other powers specified in Section 8 are the basis for most of the elastic powers of Congress.

The Necessary and Proper Clause

Section 8 also specifies Congress shall have the power "to make all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all powers vested by this Constitution in the government of the United States, or in any department or officer thereof." From the Constitution's framing, the Necessary and Proper Clause has fomented debate between those who favor a strong central government or not. Originally, the clause applied narrowly to the enumerated powers. Over time, interpretations of the clause profoundly expanded the power of the federal government. This and the commerce clause are where much of the elastic, or implied, powers of Congress originate.

The Commerce Clause

The Commerce Clause of Section 8 says it is the role of Congress "To regulate commerce with foreign nations, and among the several states, and with the Indian Tribes." The power of Congress to regulate commerce has tremendously broadened. According to Georgetown University Law Professor Randy Barnett, regulate originally meant to "make regular," or simply to "specify" how an activity may be transacted" between individuals of one state to another. Congress has instead assumed sweeping powers far beyond the Founders' original intent.

Other Congressional Powers

Congress has other constitutional powers. For example, it determines the manner of accepting new states and territories and has the power to propose amendments to the Constitution, subject to ratification by three-quarters of the states. The Senate can reject a presidential appointment. Both chambers of Congress may hold hearings, call witnesses and establish investigative committees. With its control over spending, the House of Representatives can derail implementation of federal law simply by denying funds. Congress appoints the president and vice-president when there is no majority of electoral votes and can impeach them.