He entered the Prussian judicial service in 1880 and after positions in Zabrze (Upper Silesia) and Magdeburg became Kammergerichtsrat in Berlin in 1906.

At the same time, Schiffer was a delegate to the lower chamber of the Prussian diet for the National Liberal Party (1903-1918) and a member of the Reichstag from 1912 to 1917.

[1] From February 1919 until his resignation in April 1919, Schiffer was deputy to Ministerpräsident Philipp Scheidemann and Minister of Finance in the first democratically elected German government.

During his time in office, Schiffer developed a temporary tax regime that provided the basis for what later became known as Erzbergersche Finanzreformen (named after Matthias Erzberger).

[1] After retiring from politics, Schiffer focused on heading the Berliner Verwaltungsakademie, the first institution of higher learning for the German civil service, which he had help found in 1921.

He also practiced law, served as an adviser to the bank "Bankhaus Mendelssohn & Co." and was chairman of the board at Anhaltischen Kohlenwerke AG.

[1] After the end of the Second World War, together with his son-in-law Waldemar Koch and Wilhelm Külz, Schiffer founded the Liberaldemokratische Partei Deutschlands (LDPD) in the Soviet-occupied sector of Berlin.

For three years after August 1945, Schiffer headed the central administration of Justice (Justizverwaltung) under the Soviet military government.