On March 26, 1975, the Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and on their Destruction went into force. Today, 162 countries have signed the Convention, pledging never "to develop, produce, stockpile or otherwise acquire or retain" biological weapons. Some signatory nations, however, have reserved the right to hold certain biological weapons for "prophylactic" purposes. Learn more about the UN Biological Weapons Convention.

US Supreme Court Justice Sandra Day O'Connor was born in El Paso, Texas on March 26, 1930.