Espionage Act of 1917
, legislation in the United States prohibiting espionage for a foreign country and providing heavy penalties for such activity. The law provided steep fines and imprisonment for giving national defense information to a foreign power and for interfering with the recruitment or loyalty of the armed forces. It also prohibited using the U.S. mail for material urging treason or resistance to U.S. laws, set penalties for sabotage, regulated the movement of neutral ships in U.S. waters, and prohibited the fraudulent use of passports and the unauthorized representation of a foreign government. The 1940 revision of the Espionage Act increased its penalties.