John Berne Hannum (March 19, 1915 – April 23, 2007) was a United States federal judge.
Born in Chester, Pennsylvania, Hannum received an LL.B. from Dickinson School of Law in 1941. He was in private practice in Chester from 1941 to 1942, and was then a U.S. Naval Reserve Lieutenant during World War II, from 1942 to 1946, returning to private practice in Chester from 1946 to 1949. He was in private practice in Philadelphia, Pennsylvania from 1949 to 1968. He was then a judge on the Superior Court of Pennsylvania from 1968 to 1969.
On March 24, 1969, Hannum was nominated by President Richard Nixon to a seat on the United States District Court for the Eastern District of Pennsylvania vacated by Francis L. Van Dusen. Hannum was confirmed by the United States Senate on May 5, 1969, and received his commission on May 6, 1969. He assumed senior status on May 29, 1984. Hannum served in that capacity until his death, in Unionville, Pennsylvania.
A notable sentencing by Judge Hannum was that of George Martorano. In 1984, Hannum sentenced Martorano to life in prison without parole after Martorano plead guilty to 19 counts of drug possession and distribution. As of 2014, he is the longest serving inmate for a non-violent offense at 31 years served thus far. The length of this sentence has led to criticism of Hannum's. despite Martorano's many appeals, Hannum's decision has been upheld in court.