Beugnot entered politics in 1841 as a Peer of France, was Deputy for Haute-Marne in the Chamber of 1849, and, under the Second Empire, went into a retirement that lasted until his death.
The Villemain educational plan of 1844 to subject the heads of independent institutions to the jurisdiction of the university to impose upon their pupils the obligation of making their studies in rhetoric and philosophy in certain prescribed establishments was opposed by Beugnot on liberal principles, whilst others opposed it on religious grounds.
Beugnot, who had destroyed the draft of a speech in support of the Villemain programme, was welcomed by the Catholics as a labourer entering the vineyard at the eleventh hour.
As drafter of the Law of 1850 on Liberty of Teaching, he vainly endeavoured to prevent the return of the bill to the Council of State, 7 November 1849, and in the decisive debate (14 January to 15 March 1850) he seconded the efforts of Montalembert, Parieu, and Thiers which resulted in victory for the Catholics.
Beugnot shared with François Mignet the prize of the Académie des Inscriptions (1818) for the best essay on the institutions of St. Louis.
He produced editions of the Assizes of Jerusalem (1841–43), of Beaumanoir's book of the Customs of Beauvaisis (1842), and of Les Olim ou Registres des Arrêts, or ancient registers of the Parlement of Paris (1839–48).