Career
Ordained in 1898, in March 1930 he was appointed Coadjutor Bishop of Limburg and Titular Bishop of Sebastopolis in Armenia. In June 1930 he was ordained Titular Bishop of Sebastopolis in Armenia, and he became Bishop of Limburg that October. Amid 1941 Catholic protests over Nazi euthanasia led by Bishop August von Galen of Munster, Hilfrich wrote to Franz Gürtner, the German Minister for Justice, to denounce the murders, calling them an "injustice that cries out to heaven".
Petition of Bishop of Limburg to the Reich Minister of Justice Concerning Killing of Patients at the State Hospital for the Mentally Illinois at Hadamar 13 August 1941.