The McClintock Riots occurred June 2, 1847 after two slave owners from Maryland crossed the border to claim their fugitive slaves who had reached Carlisle, Pennsylvania.  The slave owners, James Kennedy and Howard Hollingsworth, broke into a house to obtain three fugitives, a father and his ten-year-old daughter and the wife of a free black man in town. Consequently, the two Marylanders were arrested for breaking and entering.  While in jail, they wanted to know if their "property" would also be placed in custody.  The sheriff complied and when Kennedy and Hollingsworth posted bail, they took possession of the runaways, appalling the black community in Carlisle.

John McClintock, a professor at the local Dickinson College, was walking in the town and upon learning of the developments became enraged.  He entered the courthouse and declared the sheriff's actions to be illegal under a new Pennsylvania state law passed just eight weeks before on March 3, 1847. Under this law, though they could not obstruct "slavechasers" from other states in a search, Commonwealth officers could not grant a warrant or in any way assist the slave owners in taking such fugitives out of Pennsylvania.  Apparently, McClintock was the only one to know about this law and the sheriff demanded to have a copy of it.  Although McClintock produced a copy, the presiding judge, Samuel Hepburn, gave custody of the slaves back to their owners.  The black community tried to prevent Kennedy and Hollingsworth from taking custody of the three fugitives; on June 30, 1847, as the group were leaving the court house, widespread brawling ensued.  During the chaos, Kennedy suffered serious injuries from which he died a week later.

McClintock was charged for provoking the disturbances.  Two months later, he and twenty-six African-American citizens of Carlisle were tried on August 25, 1847 before the same Judge Hepburn.  McClintock and thirteen of the citizens were acquitted of all charges, but ten of the other thirteen were imprisoned and fined.  McClintock appealed to the Supreme Court of Pennsylvania, which overturned the court decision and acquitted all participants. 

The affair saw much of the local citizenry labeling McClintock as an abolitionist, while Dickinson students, not necessarily in agreement with his beliefs on slavery, overcame their early dismay and published a strong statement which proclaimed their faith in him and his innocence to the charges against him.  A year later, however, McClintock resigned from Dickinson College to take up the post of editor of the Methodist Quarterly Review.