3. c. 81) titled "An Act to prevent Unlawful Combinations of Workmen", prohibited trade unions and collective bargaining by British workers.

The 1799 and 1800 acts were passed under the government of William Pitt the Younger as a response to Jacobin activity and the fear of then-Home Secretary the Duke of Portland that workers would strike during a conflict to force the government to accede to their demands.

[1] Under these laws any combination of two or more masters, or two or more workmen, to lower or raise wages, or to increase or diminish the number of hours of work, or quantity of work to be done, was punishable at common law as a misdemeanor.

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.