In Christiana, Pennsylvania, a group of African Americans and white abolitionists skirmish with a Maryland posse intent on capturing four fugitive slaves hidden in the town. The violence came one year after the second fugitive slave law was passed by Congress, requiring the return of all escaped slaves to their owners in the South. One member of the posse, landowner Edward Gorsuch, was killed and two others wounded during the fight. In the aftermath of the so-called Christiana Riot, 37 African Americans and one white man were arrested and charged with treason under the provisions of the Fugitive Slave Law. Most were acquitted.
In February 1793, Congress passed the first fugitive slave law, requiring all states, including those that forbade slavery, to forcibly return slaves who had escaped from other states to their original owners. The law stated that "no person held to service of labor in one state, under the laws thereof, escaping into another, shall, in consequence of any law or regulation therein, be discharged from such service or labor, but shall be delivered up on claim of the party to whom such service or labor may be due."
As Northern states abolished slavery, most relaxed enforcement of the 1793 law, and many passed laws ensuring fugitive slaves a jury trial. Several Northern states even enacted measures prohibiting state officials from aiding in the capture of runaway slaves or from jailing the fugitives. This disregard of the first fugitive slave law enraged Southern states and led to the passage of a second fugitive slave law as part of the "Compromise of 1850" between North and South.
The second fugitive slave law called for the return of slaves "on pain of heavy penalty" but permitted a jury trial under the condition that fugitives be prohibited from testifying in their own defense. Fugitive slave trials like the Dred Scott case of 1857 stirred up public opinion on both sides of the Mason-Dixon Line. Meanwhile, fugitive slaves circumvented the law through the "Underground Railroad," a network of persons, primarily free African Americans, who helped fugitives escape to freedom in the Northern states or Canada.