The Treasons Act 1649 or Act declaring what offences shall be adjudged Treason was passed on 17 July 1649 by the Rump Parliament during the Commonwealth of England. It superseded the Act declaring what offences shall be adjudged Treason passed about two months earlier on 14 May 1649.
The acts was deemed necessary because the Commonwealth was a republic, so treason against the person of the king had no meaning and there were specific threats that faced the Commonwealth that this treason act helped to address.
Since the treason acts, like all acts and ordinances passed by Parliament during the Civil War and the Interregnum, did not have Royal Assent, they were deemed to be null and void following the Restoration of the monarchy in 1660.