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.