Powers of the United States Congress are implemented by the United States Constitution, defined by rulings of the Supreme Court, and by its own efforts and by other factors such as history and custom. It is the chief legislative body of the United States. Some powers are explicitly defined by the Constitution and are called enumerated powers; others have been assumed to exist and are called implied powers.
Article I of the Constitution sets forth most of the powers of Congress, which include numerous explicit powers enumerated in Section 8. Constitutional amendments have granted Congress additional powers. Congress also has implied powers derived from the Necessary and Proper Clause of the Constitution.
Congress has authority over financial and budgetary matters, through the enumerated power to lay and collect taxes, duties, imposts and excises, to pay the debts and provide for the common defense and general welfare of the United States. The Sixteenth Amendment, ratified in 1913, extended power of taxation to include income taxes. The Constitution also grants Congress exclusively the power to appropriate funds. This power of the purse is one of Congress' primary checks on the executive branch. Other powers granted to Congress include the authority to borrow money on the credit of the United States, regulate commerce with foreign nations and among the states, and coin money. Generally both Senate and House have equal legislative authority although only the House may originate revenue bills and, by tradition, appropriation bills.
The Constitution also gives Congress an important role in national defense, including the exclusive power to declare war, to raise and maintain the armed forces, and to make rules for the military. Some critics charge that the executive branch has usurped Congress's Constitutionally-defined task of declaring war. While historically presidents initiated the process for going to war, they asked for and received formal war declarations from Congress for the War of 1812, the Mexican–American War, the Spanish–American War, World War I, and World War II, although President Theodore Roosevelt's military move into Panama in 1903 did not get Congressional assent. Presidents have initiated war without Congressional war declarations for the Korean War, the Vietnam War, and described these conflicts as "police actions". In 1970, Time magazine noted: "All told, it has been calculated, U.S. presidents have ordered troops into position or action without a formal congressional declaration a total of 149 times" before 1970. In 1993, one writer noted "Congress's war power has become the most flagrantly disregarded provision in the Constitution," and that the "real erosion (of Congressional authority to declare war) began after World War II." President George H. W. Bush claimed he could begin Operation Desert Storm and launch a "deliberate, unhurried, post–Cold War decision to start a war" without Congressional approval. Critics charge that President George W. Bush largely initiated the Iraq War with little debate in Congress or consultation with Congress, despite a Congressional vote on military force authorization. Disagreement about the extent of congressional versus presidential power regarding war has been present periodically throughout the nation's history.
Congress also has the power to establish post offices and post roads, issue patents and copyrights, fix standards of weights and measures, establish courts inferior to the Supreme Court, and "To make all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this Constitution in the government of the United States, or in any department or officer thereof." Article Four gives Congress the power to admit new states into the Union.
One of the foremost non-legislative functions of the Congress is the power to investigate and to oversee the executive branch. Congressional oversight is usually delegated to committees and is facilitated by Congress' subpoena power. Some critics have charged that Congress has in some instances failed to do an adequate job of overseeing the other branches of government. In the Valerie Plame Wilson episode sometimes known as the Plame affair, some critics, including Representative Henry A. Waxman, charged that Congress was not doing an adequate job of oversight in this case. Other critics charge Congress was lax in its oversight duties regarding presidential actions such as warrantless wiretapping, although others respond that Congress did investigate the legality of decisions by President George W. Bush involving such matters.
Congress also has the exclusive impeachment power, allowing impeachment, trial, and removal of the President, federal judges and other federal officers.
Among the powers specifically given to Congress in Article I Section 8, are the following:To lay and collect taxes, duties, imposts and excises, to pay the debts and provide for the common defense and general welfare of the United States; but all duties, imposts and excises shall be uniform throughout the United States;
To borrow money on the credit of the United States;
To regulate commerce with foreign nations, and among the several states, and with the Native American tribes;
To establish a uniform rule of naturalization, and uniform laws on the subject of bankruptcies throughout the United States;
To coin money, regulate the value thereof, and of foreign coin, and fix the standard of weights and measures;
To provide for the punishment of counterfeiting the securities and current coin of the United States;
To establish post offices and post roads;
To promote the progress of science and useful arts, by securing for limited times to authors and inventors the exclusive right to their respective writings and discoveries;
To constitute tribunals inferior to the Supreme Court;
To define and punish piracies and felonies committed on the high seas, and offenses against the law of nations;
To declare war, grant letters of marque and reprisal, and make rules concerning captures on land and water;
To raise and support armies, but no appropriation of money to that use shall be for a longer term than two years;
To provide and maintain a navy;
To make rules for the government and regulation of the land and naval forces;
To provide for calling forth the militia to execute the laws of the union, suppress insurrections and repel invasions;
To provide for organizing, arming, and disciplining, the militia, and for governing such part of them as may be employed in the service of the United States, reserving to the states respectively, the appointment of the officers, and the authority of training the militia according to the discipline prescribed by Congress;
To exercise exclusive legislation in all cases whatsoever, over such District (not exceeding ten miles (16 km) square) as may, by cession of particular states, and the acceptance of Congress, become the seat of the government of the United States, and to exercise like authority over all places purchased by the consent of the legislature of the state in which the same shall be, for the erection of forts, magazines, arsenals, dockyards, and other needful buildings.
Other congressional powers have been granted, or confirmed, by constitutional amendments. The Thirteenth (1865), Fourteenth (1868), and Fifteenth Amendments (1870) gave Congress authority to enact legislation to enforce rights of African Americans, including voting rights, due process, and equal protection under the law. Generally militia forces are controlled by state governments, not Congress.
Congress also has implied powers, which derive from the Necessary and Proper Clause of the Constitution and permit Congress "To make all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this Constitution in the government of the United States, or in any department or officer thereof." Broad interpretations of this clause and of the Commerce Clause, the enumerated power to regulate commerce, in rulings such as McCulloch v Maryland, have effectively widened the scope of Congress' legislative authority far beyond that prescribed in Section 8.