Article 1 of the U.S. Constitution creates Congress and gives it every federal lawmaking power. It is the longest article in the document, and it does four things in order: it sets up the House and the Senate, spells out how they pass laws, lists what Congress can do, and lists what neither Congress nor the states can do.1Congress.gov. Overview of Legislative Vesting Clause
Two Chambers, Built Differently on Purpose
Congress has two houses, and the Framers designed them to behave differently.
The House of Representatives is the chamber closest to voters. Members serve two-year terms, so the entire body faces election on a short cycle. A representative has to be at least 25 years old, a U.S. citizen for at least seven years, and a resident of the state they represent.2Congress.gov. U.S. Constitution Article I Section 2 The House chooses its own Speaker, who runs the chamber and stands second in the presidential line of succession. Seats are divided among the states by population, so bigger states get more representatives.
The Senate is slower and more deliberate. Every state gets two senators regardless of population, and senators serve staggered six-year terms. To serve, a senator must be at least 30 years old, a citizen for at least nine years, and a resident of the state.3Congress.gov. Article I Section 3 Originally state legislatures picked senators; the Seventeenth Amendment, ratified in 1913, moved that choice to direct election by voters.4Congress.gov. Seventeenth Amendment The Vice President presides over the Senate but only votes to break a tie, and a President pro tempore takes the chair when the Vice President is absent.
Each chamber sets its own internal rules. A majority is needed to conduct business, and either chamber can expel a member by a two-thirds vote.5Constitution Annotated. U.S. Constitution Article I Section 5 Members are shielded by the Speech and Debate Clause from being sued or prosecuted over what they say during legislative business.6Constitution Annotated. Article I Section 6 Clause 1
How a Bill Becomes Law
A bill has to pass both the House and the Senate in identical form before it goes to the President. Revenue-raising bills have to start in the House, not the Senate, because the Framers wanted tax decisions to begin with the chamber elected most directly.7Congress.gov. Article I Section 7
Once a bill reaches the President, four things can happen. The President can sign it, and it becomes law. The President can veto it, and Congress can override that veto with a two-thirds vote in each chamber. The President can do nothing for ten days (not counting Sundays), and the bill becomes law without a signature. Or, if Congress adjourns during those ten days and the President has not signed, the bill dies. That last outcome is called a pocket veto, and Congress cannot override it.7Congress.gov. Article I Section 7
The Impeachment Power
Impeachment is split between the two chambers. Only the House can bring impeachment charges against a federal official.8Congress.gov. Overview of Impeachment Once the House votes to impeach, the Senate holds the trial. Conviction requires a two-thirds vote of the senators present, which is why very few federal officials have ever been convicted.9Congress.gov. Article I Section 3 Clause 6
When the person on trial is the President, the Chief Justice of the Supreme Court presides instead of the Vice President, so a Vice President never runs a trial that could put them in the Oval Office.10Constitution Annotated. Historical Background on Impeachment Trials The Senate’s punishment is limited: removal from office, and optionally a separate vote to bar the person from future federal office. It cannot impose fines or prison time.11U.S. Senate. About Impeachment
Census, Apportionment, and Elections
Article 1 requires a population count every ten years. The results determine how many House seats each state gets, which is why some states pick up seats and others lose them after each census.12Congress.gov. Article I Section 2 Clause 3 The original text included the Three-Fifths Compromise for counting enslaved people; the Fourteenth Amendment, ratified after the Civil War, replaced it with a full and equal count of all persons.
State legislatures set the times, places, and manner of congressional elections, but Congress can override those rules at any time. That is how there is a single national Election Day.13Congress.gov. Elections Clause Congress also has to meet at least once a year.14Congress.gov. Article I Section 4 When a Senate seat opens up, the governor of the state calls a special election, and most states also let the governor appoint someone to fill the seat temporarily.15Congressional Research Service. U.S. Senate Vacancies: How Are They Filled?
What Congress Can Do
Section 8 lists the specific things Congress is authorized to do. These are not general grants of power; they are the enumerated boundaries of federal lawmaking.16Congress.gov. Article I Section 8
On money, Congress can lay and collect taxes (which must be uniform across the states), borrow on the credit of the United States, coin money and set its value, and fix standards for weights and measures. On trade, the Commerce Clause lets Congress regulate commerce with foreign nations and among the states, and courts have read it broadly enough to reach a wide range of economic activity.17Congress.gov. Overview of Commerce Clause On defense and foreign policy, only Congress can declare war, and it funds and writes the rules for the armed forces; military appropriations are capped at two years so no standing army stays funded without a fresh vote. Congress can also call up state militias, and it can punish piracy and offenses against international law.18Legal Information Institute. Define and Punish Clause: Doctrine and Practice
Congress also writes the rules for how immigrants become citizens, sets uniform bankruptcy laws, runs the postal system, and issues patents and copyrights that give inventors and authors exclusive rights for limited terms.
The last item in Section 8 is the Necessary and Proper Clause, which lets Congress pass laws needed to carry out any of the other powers on the list.19Congress.gov. Overview of Necessary and Proper Clause It is the reason Congress can legislate on subjects the Framers never imagined without needing a new constitutional amendment every time.
What Congress Cannot Do
Section 9 lists restrictions on Congress itself, and some are among the strongest civil liberties protections in the Constitution.20Constitution Annotated. Article I Section 9
Congress cannot suspend habeas corpus (the right to challenge unlawful detention in court) except during rebellion or invasion when public safety requires it. It cannot pass a bill of attainder, which is a law punishing a specific person without a trial. It cannot pass ex post facto laws, meaning it cannot make conduct criminal after the fact. It cannot tax goods exported from any state.21Constitution Annotated. Export Clause and Taxes It cannot grant titles of nobility, and federal officials cannot accept gifts or titles from foreign governments without congressional approval under the Foreign Emoluments Clause.
Section 9 also contains the Appropriations Clause, which is the practical foundation of congressional power over the rest of the government: no money leaves the Treasury unless Congress has passed a law authorizing the spending.22Constitution Annotated. Overview of Appropriations Clause A President can propose a budget, but only Congress can fund it.
What States Cannot Do
Section 10 keeps individual states from acting like independent countries.23Constitution Annotated. Article I Section 10 States cannot make treaties, coin money, or issue paper currency. They cannot pass bills of attainder or ex post facto laws, and they cannot pass laws that impair existing contracts, a rule aimed at the debtor-relief statutes some states enacted in the 1780s. They cannot grant titles of nobility.
Other actions need congressional consent. States cannot tax imports or exports beyond what their inspection systems actually cost, and any surplus from those charges goes to the federal Treasury. They cannot keep troops or warships in peacetime, enter agreements with other states or with foreign governments, or go to war unless they are actually being invaded. Together, these limits make the United States a single nation for purposes of foreign policy, currency, and interstate dealings, which was the problem Article 1 was written to fix.