The Biological Weapons Convention (BWC), or Biological and Toxin Weapons Convention (BTWC), is a disarmament treaty that effectively bans biological and toxin weapons by prohibiting their development, production, acquisition, transfer, stockpiling and use. The treaty's full name is the Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and on their Destruction.Having entered into force on 26 March 1975, the BWC was the first multilateral disarmament treaty to ban the production of an entire category of weapons of mass destruction. The convention is of unlimited duration. As of January 2022, 183 states have become party to the treaty. Four additional states have signed but not ratified the treaty, and another ten states have neither signed nor acceded to the treaty.The BWC is considered to have established a strong global norm against biological weapons. This norm is reflected in the treaty's preamble, which states that the use of biological weapons would be "repugnant to the conscience of mankind". It is also demonstrated by the fact that not a single state today declares to possess or seek biological weapons, or asserts that their use in war is legitimate. In light of the rapid advances in biotechnology, biodefense expert Daniel Gerstein has described the BWC as "the most important arms control treaty of the twenty-first century". However, the convention's effectiveness has been limited due to insufficient institutional support and the absence of any formal verification regime to monitor compliance.