When federal government agencies and programs lack budget authority, they experience a "funding gap." Under the Antideficiency Act (31 U.S.C. § 1341 et seq.), they must cease operations, except in certain circumstances. When there is a funding gap that affects many federal entities, the situation is often referred to as a government shutdown. In the past, there have occasionally been government shutdowns, the longest of which lasted 21 days, from December 16, 1995, to January 6, 1996.