John Reed was born in 1786 on Marsh Creek, in Adams County, the son of General William Reed. He entered Dickinson College in Carlisle, Pennsylvania with the class of 1806 but left before graduation to study law with William Maxwell of nearby Gettysburg. Reed was admitted to the bar and began practice in Westmoreland County. He quickly made a name for himself there and in 1815 he was elected to the Pennsylvania Senate and served as Deputy Attorney General for the state. In July 1820, Governor Findlay named him the President Judge of the Ninth Judicial District, comprising Cumberland, Franklin, Adams, and Perry counties.
Living in Carlisle, Reed penned his three volume legal classic Pennsylvania Blackstone and began to teach. From 1821 to 1828 he served on the Dickinson College Board of Trustees. In 1833, as his new house was being completed on the corner of West and High Streets in Carlisle, Judge Reed contacted the new trustees of Dickinson College, across the street. He had previously suggested the teaching of law in connection with the College but the institution's brief closing killed this idea. Active in the local conversations over the reopening of Dickinson, he proposed a course of study in the law that would result in a bachelor of law degree. Reed would deliver a series of rigorous instruction in the theory and practice of the law for those seeking this degree while more general instruction in the way that the law worked would be offered to other students at the College. Even further, a "Moot Court" would be conducted, affording students the chance to hone their skills through mock courtroom proceedings. The Board of Trustees, keen to gain all opportunities for the successful relaunch of the College, agreed swiftly and classes, held in his new house, began in April 1834.
Leaving the District Court and returning to private practice in 1839, Reed found the burdens of specialists and non-specialists increasingly heavy, and induced the College to cease the general legal information lectures in 1840. His formal instruction continued to be a remarkable success, and graduated more than a hundred students, including two later Civil War governors, Andrew Curtin and Alexander Ramsey, as well as future state chief justices and Civil War generals.
Judge John Reed died in January 1850. The Dickinson student body wore mourning badges for the following thirty days in his honor. Law classes were ended, not to be resumed until 1862, under Judge Graham. In 1890, Dickinson President George Reed (no relation) placed the Dickinson School of Law again on a firm footing, separate but closely affiliated with College.
John Reed and his wife Sarah had a daughter, Anna Mathilda Reed. Their house was purchased as the residence of President Reed in 1890 and has served since as the home of the College President. John Reed and his family are buried in the Old Grave Yard in Carlisle.