Career
He served for 12 years as the chairman of the German Confederation of Trade Unions (DGB). Born in Büderich, now part of Meerbusch, North Rhine-Westphalia, Sommer studied political sciences at Free University of Berlin from 1971 to 1980. After his final degree, Sommer worked for the trade union.
He climbed the ladder in the trade union becoming chairman of ver.di on 18 March 2001.
A year later, on 28 May 2002, he was elected chairman of the DGB. He served for twelve years, retiring in 2014.
