The Fugitive Slave Law was passed by Congress as part of the Compromise of 1850 between the Southern slave interest and Northern Free Soil movement.The Fugitive Slave Act was one of the most controversial provisions of the 1850 compromise and heightened Northern fears of a 'slave power conspiracy'.
By 1843, several hundred slaves a year were successfully escaping to the North, making slavery an unstable institution in the border states.The Fugitive Slave Act of 1793 required the return of runaway slaves by forcing the authorities in free states to return fugitive slaves to their masters.However, many Northern states found ways to circumvent the Fugitive Slave Act.Some jurisdictions passed "personal liberty laws," which mandated a jury trial before alleged fugitive slaves could be moved. Others forbade the use of local jails or the assistance of state officials in the arrest or return of alleged fugitive slaves.In some cases, juries refused to convict individuals who had been indicted under the Federal law.
The Missouri Supreme Court held that the voluntary transportation of slaves into free states, with the intent of residing there permanently or definitely, automatically made them free, while the Fugitive Slave Law dealt with slaves who went into free states without their master's consent.Furthermore, the U.S. Supreme Court ruled, in Prigg v. Pennsylvania (1842), that states did not have to offer aid in the hunting or recapture of slaves, which greatly weakened the law of 1793.These and other northern attempts to sidestep the 1793 legislation agitated the South, who sought stronger federal provisions for returning slave runaways.
In response to the weakening of the original fugitive slave act, the Fugitive Slave Law of 1850 made any Federal marshal or other official who did not arrest an alleged runaway slave liable to a fine of $1,000.Law-enforcement officials everywhere now had a duty to arrest anyone suspected of being a runaway slave on no more evidence than a claimant's sworn testimony of ownership.The suspected slave could not ask for a jury trial or testify on his or her own behalf.In addition, any person aiding a runaway slave by providing food or shelter was subject to six months' imprisonment and a $1,000 fine.Officers who captured a fugitive slave were entitled to a bonus or promotion for their work.Slave owners only needed to supply an affidavit to a Federal marshal to capture an escaped slave.Since any suspected slave was not eligible for a trial, many free black people were conscripted into slavery as they had no rights in court and could not defend themselves against accusations.
The Fugitive Slave Act was unilaterally met with violence and uproar in the North.This anger stemmed less from the fact that slavery existed than from Northern fury at being coerced into protecting the Southern slave institution.Moderate abolitionists were faced with the choice of defying what they believed to be an unjust law or breaking with their own consciences and beliefs, and many became radical antislavery proponents as a result.Many northerners viewed the 1850 Fugitive Slave Law as evidence that the South was conspiring to spread slavery through federal coercion and force, regardless of the will of northern voters.Violence therefore became an acceptable response to the Fugitive Law--and many northern towns witnessed attacks on slave catchers and mobs setting free captured fugitives, as in the 1851 cases of John McHenry in Syracuse, NY and Shadrach Minkins in Boston.