James Aloysius Coolahan (April 26, 1903 – July 16, 1986) was a United States federal judge.
Born in Hoboken, New Jersey, Coolahan received an LL.B. from Rutgers University School of Law in 1925. He was a law clerk from 1925 to 1927. He was in private practice in Jersey City, New Jersey from 1927 to 1949. He was a First assistant corporation counsel, City of Hoboken, New Jersey from 1932 to 1943. He was a judge on the Hudson County Court, New Jersey from 1949 to 1956. He was a judge on the Superior Court of New Jersey from 1956 to 1962.
Coolahan was a federal judge on the United States District Court for the District of New Jersey. Coolahan was nominated by President John F. Kennedy on February 19, 1962, to a seat vacated by Mendon Morrill. He was confirmed by the United States Senate on April 2, 1962, and received his commission on April 7, 1962. He served as chief judge from 1972-1973. He assumed senior status on June 1, 1974. Coolahan served in that capacity until July 16, 1986, due to his death.
He died in Spring Lake, New Jersey.