His sister was the war correspondent and novelist Martha Gellhorn, and his younger brother Alfred was an oncologist and dean of the University of Pennsylvania School of Medicine.
[7] On January 15, 1942, he joined the Office of Price Administration (OPA) as assistant general counsel and chief attorney of the New York regional staff.
[6][10] In 1975, Gellhorn retired to emeritus status, and the May 1975 issue of the Columbia Law Review was dedicated to him,[11] with articles praising him written by Michael I. Sovern,[12] Harry W. Jones,[13] Harold Leventhal,[14] Erwin N. Griswold,[5] and Jack Greenberg.
[15] He served on the Administrative Conference of the United States from 1968 until his death,[6] and was honored at the evening reception at its June 1988 plenary session.
[17] The April 1996 issue of the Columbia Law Review contained articles praising him by Clark Byse,[18] Warner W. Gardner,[19] Louis Lusky,[20] and Peter L.