In 1837, Edward Prigg (defendant) captured Margaret Morgan and her children in Pennsylvania. Prigg claimed that Morgan was a fugitive slave. Pennsylvania was a non-slave-holding state and was a common refuge for fugitive slaves. The federal Fugitive Slave Act of 1793 authorized the owner of a fugitive slave to seize the slave and bring the slave before a federal judge or state magistrate to obtain a certificate after proving that the slave was actually a fugitive slave. Prigg did not prove that Morgan was a slave before any federal judge or state magistrate in Pennsylvania. Instead, Prigg forcibly removed Morgan and her children to Maryland, where a county judge adjudged them to be slaves. Prigg was charged and convicted under a Pennsylvania law designed to prevent self-help in the return of fugitive slaves. Prigg challenged this law as unconstitutional.