 On July 2, 1947, Mayor William O'Dwyer appointed him as city magistrate of New York City to fill a vacancy; later that month he was appointed to a full ten-year term.As the result of a one-day shortage of magistrates in March 1948, Lanzetta attracted notice by presiding in five courts in five hours and disposing of 500 cases, 400 of which were in the Downtown Traffic Court.He served as city magistrate until May 26, 1948, when Mayor O'Dwyer appointed him to a ten-year term as a justice of the city Domestic Relations Court.