Advocates of anti-slavery responded to the Fugitive Slave Law of 1850 by refusing to follow it.
The Fugitive Slave Law, which was part of the Compromise of 1850, was supposed to compel Northern citizens to help return runaway slaves to their owners in the South. However, many abolitionists (people who wanted to get rid of slavery) ignored this law by not reporting runaway slaves or actually helping them escape to another state/country. This helped to increase tension between Northerners and Southerners.