The American Clean Energy and Security Act would have established the first national cap-and-trade system for greenhouse gas emissions, requiring major emitters to hold permits for every ton of carbon released. It was the first climate bill ever to pass either chamber of Congress, passing the House by the narrowest margin of any bill in this archive. The Senate never brought it to a floor vote. Senate Majority Leader Harry Reid did not schedule it, facing a threatened Republican filibuster. The bill expired when the 111th Congress ended on January 3, 2011.

Primary source: https://www.congress.gov/bill/111th-congress/house-bill/2454