Philippe Jacques Rühl (3 May 1737 – 29/30 May 1795) was a German-French statesman during the French Revolution, best remembered as the doyen d'âge (oldest deputy) of the opening session of the Convention of 1792–1795.
Born in Strasbourg, a son of a Lutheran minister. He studied theology at the University of Strasbourg. He later served as director of gymnasium at Durckheim, Germany, then as a tutor at the princely court of Leinigen-Dachsburg (Linange-Hartenbourg). As court counselor, he participated in settling succession dispute with the Italian branch of the family.
He was elected (31 August 1791) as a representative of Bas-Rhin to the Legislative Assembly (1791–1792). He sat with the extreme left wing of the deputies and served as a deputy member of the Extraordinary Commission of Twelve (18 June 1792 – 21 September 1792).
Elected (4 September 1792) to the Convention (1792–1795) as a deputy for Bas-Rhin, he presided at the first session of the Convention as the oldest deputy present (20 September 1792). He continued to ally himself with the more radical section of deputies, joining the Montagnard faction. However, he was absent from the Convention during the trial of King Louis XVI. He would go on to serve a full term as President of the Convention from 6 March 1794 until 21 March 1794.
Rühl served as a member of the Committee of General Security (14 September 1793 – 31 August 1794). He was dispatched as Representative on a Mission to departments of Marne and Haute-Marne (16 September 1793 – 3 November 1793) to assist in arranging the levée en masse (military conscription). While on this mission he showed his revolutionary zeal by breaking the so-called Holy Ampulla (8 October 1793) – the Holy Ampulla had been a vessel containing the sacred oil for anointment of the French kings at Reims. He served in a second mission to Bas-Rhin (23 Nov 1793 – 8 Jan 1794) for organizing the district of Neu-Saarwerden.
Rühl was designated for yet another mission, this time to Bas-Rhin and Haut-Rhin, 24 July 1794, but did not depart until 1 August 1794, and so he was in Paris to witness the fall of Robespierre. He returned 25 August 1794.
He participated in the Revolt of 1 Prairial Year III (20 May 1795), addressing the insurgents with the words "Du pain et la Constitution de 1793!" ("Bread and Constitution of 1793!"). This action threatened the new conservative order, and he was threatened with indictment, but in the end was sentenced only to house arrest "in view of his advanced age" (he was 58). He was called before the military commission (28 May 1795) and committed suicide by stabbing himself with a dagger, a precursor of the "Martyrs of Prairial" (Romme, Goujon, Duquesnoy, Soubrany, Duroy, and Bourbotte).