German Empire

During the First World War, Schiffer was an adviser to General Wilhelm Groener and was in charge of the law department at the War Ministry. In October 1917, he became Unterstaatssekretär (Undersecretary) at the Reichsschatzamt (Treasury). 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. His oratory skills, support from big industry and his ambitious nature made him a well known deputy. He was in favor of strengthening the power of the parliament but as a monarchist opposed the revolution.^[1]

Weimar Republic

Nevertheless, after the German Revolution he became Staatssekretär at the Treasury in November 1918. From 1918 to 1919, Schiffer was a founder-member of the German Democratic Party (DDP) and was a member and leader of the DDP parliamentary group in both the Weimar National Assembly (1919–20) and the Reichstag (1920–1924). He also remained a delegate to the Landtag of Prussia until 1924.^[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] Schiffer asked Scheidemann for his dismissal from the cabinet on 28 March 1919, giving "personal reasons". He also named disagreement about the creation and filling of several public sector positions as an issue.^[2]

After the Scheidemann cabinet resigned in June 1919 over the Treaty of Versailles, the DDP initially refused to become part of the Bauer cabinet, but in early October, the Democrats rejoined SPD and Zentrum in government. As a result Schiffer became Minister of Justice and, once again, deputy to the head of government, now with the title of Vice-Chancellor. He opposed plans to socialize industries and worked towards a fundamental reform of the civil service.^[1]

However, in March 1920, during the Kapp-Lüttwitz-Putsch Schiffer did not flee the capital with the majority of the cabinet. His role over the days of the putsch was controversial. Since he negotiated with the putschists without a formal mandate from the government, made promises in the name of president Friedrich Ebert and offered those responsible for the putsch amnesty, Schiffer was forced to resign by the SPD after the end of the putsch.^[1]

From May to October 1921, Schiffer once again was Minister of Justice in the first cabinet of Joseph Wirth. In 1921-22, Schiffer was head of the German delegation at the negotiations with the Allies on Upper Silesia in Geneva that led to the treaty of 15 May 1922 securing trading rights and minority rights in the region. In 1922-23, he was the German representative at the International Court of Justice in The Hague. In 1924, Schiffer supported the acceptance of the Dawes Plan.^[1]

In 1925, he resigned from the DDP and retired from active politics after an attempt to merge the parties of the political centre in a single Liberale Vereinigung.^[1]