After the war Thorbeck worked as an attorney in Nuremberg. In 1955 he was convicted by a court of assizes in Augsburg for assisting in murder and sentenced to four years imprisonment. On 19 June 1956 the Federal Court of Justice of Germany exonerated him on grounds that the killings were 'legal' because the Nazi regime had the right to execute 'traitors'. The decision was rescinded by the Berlin State Court in 1996.