Born in Newark, New Jersey, Hartshorne received a Bachelor of Letters from Princeton University in 1909 and a Bachelor of Laws from Columbia Law School in 1912.
He was in private practice in New Jersey from 1912 to 1931, also serving in the United States Naval Reserve as a Lieutenant, J.G., during World War I, and as a Special Assistant to the United States Attorney for the District of New Jersey in 1925.
He was a Judge of the County Court in Newark from 1931 to 1951, and during that time was President of the New Jersey Interstate Commission on Crime from 1935 to 1943.
[1] On October 17, 1951, Hartshorne was nominated by President Harry S. Truman to a seat on the United States District Court for the District of New Jersey vacated by Judge Guy Leverne Fake.
Hartshorne served in that capacity until his death on September 14, 1975.