 Poniatowski served as Minister of Health from 1973 to 1974 and Minister of the Interior in the Giscard d'Estaing government from 1974 to 1977.He was a founder and honorary president of the Union for French Democracy (Union pour la Démocratie Française, UDF).Poniatowski was a great-great-great-grandson of Prince Kazimierz Poniatowski, older brother of Stanisław August Poniatowski, who reigned as king of Poland from 1764 to 1795.