What Can Congress Do?

Article I, Section 8 gives Congress the power “to declare War,” along with the power to raise and fund the armed forces. The president is commander-in-chief of those forces, but the decision to begin a war was placed with the legislature on purpose: the framers wanted the branch closest to the voters, and the one that pays for wars, to be the one that starts them.

A declaration of war is passed like any law, as a joint resolution approved by a simple majority of both chambers and signed by the president. Congress has done it eleven times, covering five wars: the War of 1812, the Mexican–American War, the Spanish–American War, World War I, and World War II. The last formal declaration was against Romania on June 5, 1942.

Every conflict since, from Korea and Vietnam to Iraq and Afghanistan, has been fought without one. Instead Congress has passed authorizations for the use of military force (AUMFs), which approve military action against a named enemy without a declaration. The 1991 Gulf War resolution, the September 2001 AUMF against those responsible for the 9/11 attacks, and the 2002 Iraq resolution are the main examples, and the 2001 AUMF is still in force.

The War Powers Resolution of 1973, passed over President Nixon’s veto, tries to keep the power in Congress: the president must notify Congress within 48 hours of sending forces into hostilities and must withdraw them within 60 days (plus a 30-day withdrawal period) unless Congress authorizes the action. Every president since has questioned its constitutionality, and Congress has rarely enforced it. Its practical tool remains the power of the purse: Congress can refuse to fund a military operation.

When the president vetoes a bill, it returns to the chamber where it started with the president’s objections. If two-thirds of the members present and voting in that chamber vote to pass it again, it goes to the other chamber; if two-thirds there agree, the bill becomes law without the president’s signature. With full attendance that is 290 of 435 in the House and 67 of 100 in the Senate.

Article II, Section 4 says the president, vice president “and all civil Officers of the United States” can be removed on impeachment for and conviction of “Treason, Bribery, or other high Crimes and Misdemeanors.” Cabinet secretaries, agency heads and federal judges are all civil officers. The attorney general, as head of the Justice Department, is one too.

The process is the same as for a president. The House investigates, then votes on articles of impeachment by a simple majority. The Senate holds a trial and votes on each article; conviction requires two-thirds of the senators present. Conviction removes the officer, and the Senate can then vote by a simple majority to disqualify them from holding federal office again.

It has happened twice to a cabinet member. In 1876 the House impeached Secretary of War William Belknap for taking kickbacks, hours after he resigned; the Senate tried him anyway and acquitted him, with a majority voting guilty but short of two-thirds. In February 2024 the House impeached Homeland Security Secretary Alejandro Mayorkas by a single vote, 214–213; the Senate voted in April 2024 that the articles did not allege an impeachable offense and dismissed them without a trial. No attorney general has been impeached, although articles have been introduced against several.

Impeachment of a cabinet member is rare for a practical reason: the president can fire a secretary at any time, and the Senate confirmed them in the first place. The more common tools are oversight hearings, subpoenas, and cutting an agency’s funding. The full set of checks is on The Role of Congress.

The question was settled in the very first impeachment. In 1797 the House impeached Senator William Blount of Tennessee for conspiring to help Britain seize Spanish territory. The Senate expelled him within days, and in 1799 it dismissed the impeachment, concluding that a senator is not a “civil officer” subject to impeachment. No member of Congress has been impeached since.

What each chamber can do is expel its own members. Article I, Section 5 lets either house “with the Concurrence of two thirds, expel a Member.” The Senate has expelled fifteen senators: Blount in 1797 and fourteen in 1861 and 1862 for supporting the Confederacy. Several others have resigned when expulsion looked likely, most recently Bob Packwood in 1995. The House has expelled six members, the most recent being George Santos in December 2023. Short of expulsion, a chamber can censure a member by majority vote, a public rebuke that leaves the seat intact (see censure).

Recall is not available. No state can recall a U.S. senator or representative: the Constitution fixes the terms and the qualifications of members, and courts have held that states cannot add a removal mechanism the Constitution does not provide. A 2010 effort to recall a New Jersey senator was stopped by that state’s supreme court on exactly that ground. Voters remove senators at the ballot box, one class at a time; see how Senate classes work.

When a Senate seat does become vacant, through death, resignation or expulsion, most states let the governor appoint a replacement until a special election. Which senators are up in the next election is on Senate term end dates.

The Supreme Court has the final word on what the Constitution means, and Congress cannot pass a law that simply reverses a constitutional ruling. What Congress can do depends on what kind of decision it is.

1. If the Court interpreted a statute, rewrite the statute. Many Supreme Court cases are about what a law Congress wrote actually means. Congress can respond by amending the law to say something different. In 2007 the Court held in Ledbetter v. Goodyear that a pay-discrimination claim had been filed too late; in 2009 Congress passed the Lilly Ledbetter Fair Pay Act to change the deadline rule. The Civil Rights Act of 1991 overrode several employment-law decisions the same way.
2. If the Court interpreted the Constitution, amend the Constitution. This requires a two-thirds vote in both chambers and ratification by three-quarters of the states, so it is rare, but it has been done. The 16th Amendment (1913) authorized the income tax after the Court struck one down; the 26th Amendment (1971) set the voting age at 18 after the Court limited Congress’s power to do so by statute; the 11th and 14th Amendments also overturned Supreme Court decisions.
3. Change the courts themselves. Congress sets the number of justices (nine since 1869, by statute, not by the Constitution), creates and abolishes the lower federal courts, controls the judiciary’s budget, and under Article III can limit the Court’s appellate jurisdiction. The Senate confirms every federal judge, and Congress can impeach and remove judges: fifteen have been impeached and eight removed.

None of these lets Congress reverse a specific case on its own. That is the intended design; see how the three branches check each other on The Role of Congress.

The 25th Amendment, ratified in 1967, handles presidential succession and disability in four sections. Section 1 makes the vice president president if the office becomes vacant. Section 2 lets a president fill a vice-presidential vacancy by nomination, subject to confirmation by a majority of both chambers of Congress; that is how Gerald Ford (1973) and Nelson Rockefeller (1974) became vice president. Section 3 lets a president voluntarily hand power to the vice president, as several have done for a few hours during surgery.

Section 4, the one people mean when they ask about “invoking” the amendment, is the involuntary route. It is triggered when the vice president and a majority of the cabinet send Congress a written declaration that the president is unable to discharge the duties of the office. The vice president immediately becomes acting president. Congress cannot start this process. The text does let Congress create by law “such other body” that could act in place of the cabinet, but it has never done so.

Congress does decide the dispute if there is one. If the president declares in writing that no inability exists, and the vice president and cabinet disagree within four days, Congress must assemble within 48 hours and vote within 21 days. The vice president stays in charge only if two-thirds of both chambers agree; otherwise the president resumes office. Section 4 has never been invoked.

• Pass a bill of attainder: a law that declares a specific person guilty and punishes them without a trial (Article I, Section 9).
• Pass an ex post facto law: one that makes an act a crime after it was committed, or increases the punishment retroactively.
• Suspend habeas corpus, except “when in Cases of Rebellion or Invasion the public Safety may require it.”
• Grant titles of nobility or tax goods exported from a state.
• Appoint executive officers or judges itself. The president nominates; the Senate can only confirm or reject.
• Remove its own members by impeachment, or let states recall them. Expulsion by two-thirds is the only route.
• Overturn a constitutional ruling by ordinary law. That takes an amendment.
• Start the 25th Amendment process against a president.

Everything else Congress does must trace back to a power the Constitution grants, either one of the enumerated powers in Article I, Section 8 (taxing, borrowing, regulating interstate commerce, coining money, raising armies, and so on) or the “necessary and proper” clause that lets it pass laws to carry those powers out. For how those powers are exercised day to day, see How Congress Works.