Justin Joseph McCarthy was born in Sayre, Pennsylvania on 26 November 1900 to Joseph and Dehlia McCarthy. He has a brother, Joseph A. McCarthy, and a sister, Mary Agnes McCarthy. The McCarthy family moved to Elizabeth, NJ, two years later, and Justin J. McCarthy attended St. Mary's School and Battin High School, and was a member of the baseball team. He attended Seton Hall College, from which he graduated in 1923, and Immaculate Conception Seminary. In 1923, after completing his studies in South Orange and Darlington, he attended the North American College in Rome, where he received a master's degree in theology. Father McCarthy was ordained 16 April 1927. On his return to the United States, Fr. McCarthy was a parish priest and a member of the faculty, then spiritual director of Immaculate Conception Seminary. In 1954, while serving as pastor of Our Lady of Sorrows Church in South Orange, he was named as Auxiliary Bishop of the Archdiocese of Newark by Pop Pius XII, and consecrated as such on 17 June 1954 by Archbishop Thomas A. Boland. Three years later he became the second Bishop of Camden, on 19 March 1957. In 1959, while visiting his sister in Hillside, NJ, he suffered a heart attack and died 26 December 1959.