The Personal Liberty Laws were passed in the 1850s by nine of the northern states in response to the Fugitive Slave Law of 1850. These laws used tactics such as forbidding the use of state jails to imprison alleged fugitives to prevent state officials from enforcing the strict law. Events and Trends Technology Production of steel revolutionised by invention of the Bessemer process Benjamin Silliman fractionates petroleum by distillation for the first time First transatlantic telegraph cable laid First safety elevator installed by Elisha Otis Science Charles Darwin publishes The Origin of Species, putting forward the theory of evolution... The Fugitive Slave Law or Fugitive Slave Act was passed by the United States Congress on September 18, 1850 as part of the Compromise of 1850 between Southern slaveholding interests and Northern Free-Soilers and abolitionists. ...

Many Northern states reacted to The Fugitive Slave Law of 1793 by enacting legislation to protect free black Americans and fugitive slaves. These "personal liberty laws" compelled a slave catcher to furnish corroborative proof that his captive was a fugitive and frequently accorded the accused the rights to trial by jury and appeal. Laws in some states made it easier to extradite a runaway if his or her slave status were confirmed. It has been suggested that Fugitive slave laws be merged into this article or section. ...

As it turned out, in general the Fugitive Slave Act was inconsistently enforced and provoked ill feeling between northern and southern states.

In Prigg v. Pennsylvania (1842), the United States Supreme Court determined that 'personal liberty laws' were unconstitutional: They interfered with the Fugitive Slave Act. The Court held that while states were not compelled to enforce the federal law, they could not override it with other enactments. Prigg v. ... 1842 was a common year starting on Saturday (see link for calendar). ...

Prigg induced numerous Northern states to amend their laws, which specified that law enforcement officials and jurists refrain from doing anything about runaway slaves. The only alternative left to slave catchers was to kidnap runaways, and then either return them to their owners, or force them to appear them before federal judges who were not held to state statutes.