The Combination Act 1799 (39 Geo. III, c. 81) titled An Act to prevent Unlawful Combinations of Workmen, prohibited trade unions and collective bargaining by British workers. The Act received royal assent on 12 July 1799. An additional Act, the Combination Act 1800, was passed in 1800 (39 & 40 Geo III c. 106).
The 1799 and 1800 acts were passed under the government of William Pitt the Younger as a response to Jacobin activity and the fear that workers would strike during a conflict to force the government to accede to their demands. Collectively these acts were known as the Combination Acts.
The legislation drove labour organisations underground. Sympathy for the plight of the workers brought repeal of the acts in 1824. Lobbying by the radical tailor Francis Place played a role in this. However, in response to the series of strikes that followed, the Combinations of Workmen Act 1825 was passed, which allowed trade unions but severely restricted their activity.