The Fugitive Slave Law of 1850 made it a crime to harbor escaped slaves, or to knowingly ignore their presence. Anyone who found an escaped slave or knew of one was required by law to report to Fedral marshals or other legal authority.

This meant that anyone wishing to avoid trouble, well-to-do or not, reported fugitives, regardless of their feelings about slavery.
In Kansas, Missouri and some other states, pro- and anti-slavery gangs attacked those holding the opposite view.

It also contributed to the creation of patrollers, the bounty hunters of their time.

The song mirrors history.