 He also served as a judge on the archdiocesan matrimonial court.On April 26, 1929, O'Hara was appointed Auxiliary Bishop of the Archdiocese of Philadelphia and Titular Bishop of "Heliopolis in Phoenicia" by Pope Pius XI.He received his episcopal consecration on the following May 21 from Cardinal Dougherty, with Bishops John Bernard MacGinley and Thomas Charles O'Reilly serving as co-consecrators, at the Cathedral of Ss.