High Quality Content by WIKIPEDIA articles! The Offences at Sea Act 1799 (39 Geo III c.37) is an Act of the Parliament of Great Britain. The long title of the Act is "An Act for remedying certain Defects in the Law respecting Offences committed upon the High Seas." It is still in force. It extended the jurisdiction of British courts to crimes committed by British subjects on the high seas. It does not apply to foreign citizens. (However crimes committed by foreigners in British territorial waters, or on board British ships on the high seas, can be prosecuted in British courts.)