Isaac René Guy le Chapelier (June 12, 1754 - 1794), was a French politician.

Isaac René Guy le Chapelier

He was born at Rennes in Brittany, where his father was botonnier of the corporation of lawyers. He entered the law, and had some success as an orator. In 1789 he was elected as a deputy to the States General by the Tiers-Etat of the senechaussée of Rennes. He adopted advanced opinions, and was one of the founders of the Jacobin Club or "Breton Club"; his influence in the Constituent Assembly was considerable, and on August 3, 1789 he was elected its president for a short term of 2 weeks.

Before the establishment of the constitutional monarchy in France in September of 1791, le Chapelier introduced a motion in the National Assembly which prohibited guilds and trade unions. Le Chapelier and other Jacobins interpreted demands by Paris workers for higher wages as contrary to the new principles of the Revolution. The measure was enacted law on June 14, 1791 (subsequently known as the 'Le Chapelier Law') and effectively barred guilds and trade unions in France until 1884.

During the Terror, he temporarily emigrated to England, but returned to France in 1794 in a hopeless effort to prevent the confiscation of his assets. He was arrested and led to the guillotine in Paris.