A markup session occurs when a legislative committee or subcommittee meets to debate, amend or rewrite a bill. The committee has the option of either accepting or rejecting the final version of the bill that comes out of the markup session.
Although either a full committee or a subcommittee of the U.S. Congress has the authority to hold a markup session, only a bill that comes out of a markup session held by a full committee goes to the appropriate legislative chamber for a vote. The full committee also gives its legislative colleagues an explanation of any changes to the bill that occur during the markup session.
A congressional markup session is distinct from a congressional hearing, where congressmen and women hear testimony from various witnesses. The hearing stage of a bill's journey to become law occurs before the markup session. Sometimes a bill that comes out of a committee during a markup session is drastically different from the original bill that was submitted. In this case, the bill gets a new number before moving on to the next stage of the process. When a bill receives a new number in this way, legislators refer to it as a "clean bill."