Abolitionist Movement
People were helping slaves escape by housing them, hiding them, and transporting them (Underground Railroad). On the other hand, men who had slaves were giving rewards for people capturing escaped slaves.
Fugitive Slave Law
Any person aiding a runaway slave by providing shelter, food or any other form of assistance was liable to six months' imprisonment and a $1,000 fine. Those officers capturing a fugitive slave were entitled to a fee and this encouraged some officers to kidnap free Negroes and sell them to slave-owners. This was a cause for the Civil War because people in the North were upset about free african americans being kidnapped.