Introduction. Anyone may draft a bill. Only Members of Congress can introduce legislation. Members introducing legislation are referred to as sponsors or co-sponsors. There are four types of legislation: bills, joint resolutions, concurrent resolutions, and simple resolutions. The official legislative process begins when a bill or resolution is numbered. Bill numbers preceded with "H.R." are House bills; bill numbers preceded with "S." are Senate bills.

Committee Referral. After a bill is numbered, it is referred to a standing committee in the House or Senate.

Committee Action. When a bill reaches a committee it is placed on that committee’s calendar. A bill can then be referred to a subcommittee or can be considered by the full committee directly. The bill is examined carefully. If a committee declines to act on a bill, the bill has little chance for passage; the committee has effectively killed the bill.

Subcommittee Review. Studies and hearings on the legislation often take place at the subcommittee level, where industry experts, public officials, legislators, lobbyists, and other participants register their support or opposition to the legislation. These participants give testimony supporting their views on the legislation, which can be given in person or may be submitted as a written statement. At this point, most committee members will register their own position on the bill, in the form of an opening statement. Legislators are able to question each witness after he or she testifies on the matter.

Mark Up. When hearings are completed, and the subcommittee leadership determines that a bill should undergo a vote, the subcommittee may move to "mark up" or make changes to, the bill before voting to report the bill to the full committee. If the subcommittee votes not to report legislation to the full committee, the bill dies.

Committee Action to Report a Bill. After a subcommittee reports a bill, the full committee can conduct further studies and hearings or it may vote on the subcommittee’s recommendations and any proposed amendments. The full committee may also "mark up" a bill in order to make amendments before it votes on its recommendation to the House or Senate floor. This procedure is called "ordering a bill reported." Should the committee fail to report the bill to the House or Senate floor, the bill dies.

Publication of a Committee Report.   After a committee votes to have a bill reported, the committee chairman instructs staff to prepare a written report on the bill. The report describes, in depth, the scope of the legislation, impact on existing laws and programs, position of the executive branch, and views of dissenting members of the committee. Report language often clarifies the intent of the bill and gives direction on how the legislation should be implemented.

Floor Action.   After a bill is reported back to the House or Senate, it is placed in chronological order on the calendar. In the House there are several different legislative calendars, and the Speaker and majority leader largely determine what order bills come up. In the Senate, there is only one legislative calendar. In either chamber, legislators may put holds on the bill to prevent a bill from coming up.

Rules Committee.   Before a bill reaches the floor of the House or Senate, it must go to the Rules Committee, which determines the rules and procedures governing the debate on legislation. The rules determine the conditions, number of amendments allowed, and amount of time allocated for general debate. Legislation may be subject to closed rules, modified closed rules, special rules, or open rules.

Floor Debate.  Depending on the rule, Members of the House or Senate are allocated time to debate legislation and offer amendments.

Voting. After the debate and the (voted) approval of any amendments, the bill is passed or defeated by the members voting by voice or by roll call.

Referral. When a bill is passed by the House or the Senate it is referred to the other chamber, where it usually follows the same route through committee or floor action. This chamber may ignore the bill, reject it, approve it as received, or amend it.

Conference. If the other chamber makes only minor changes to a bill, it is common for the legislation to go back to the first chamber for concurrence. When the other chamber makes substantive changes to the bill, a conference committee is formed to reconcile the differences between the House and Senate versions. If the conferees are unable to reach agreement, the legislation dies. If agreement is reached, a conference report is prepared, describing the committee members’ recommendations for changes. Both the House and Senate must approve of the conference report.

Final Action.   After conference, the revised bill returns to both the House and Senate in identical form. If it is approved, it is sent to the President. The President may veto the bill, sign the bill into law, or take no action on the bill. If the President takes on action on the bill for ten days while congress is in session, it automatically becomes law; if he takes no action on the bill after Congress has adjourned its second session, it is a "pocket veto" and the legislation dies.

Overriding a Veto. If the President vetoes a bill, Congress may attempt to override the veto, which requires a two-thirds roll call vote of legislators, providing sufficient numbers are present for a quorum.