He was a member of the Republican Union and later an Independent Radical.
[1][2] As President of the Senate during all of the first World War, he was a strong advocate of forcing Germany to make reparations.
[3] He co-authored a book on the history of legal enforcement, studying the use of imprisonment and deportation.
In the government of Jean Casimir-Perier, Dubost served as Minister of Justice between 1893 and 1894.
In January 1906, Armand Fallières stood down as President of the French Senate and Dubost was elected in his place.