The Fugitive Slave Act was a controversial law passed by the United States Congress in 1850 as part of the Compromise of 1850. This law required that escaped slaves be returned to their masters, even if they had reached free states in the Northern part of the country. The Act gave slaveholders and their agents broad authority to capture and return escaped slaves, and imposed penalties on anyone who aided or harbored escaped slaves.

The Fugitive Slave Act was deeply unpopular among abolitionists and free African Americans, as it essentially forced free states to participate in the enforcement of slavery. Many free African Americans in the North lived in constant fear of being kidnapped and returned to slavery under the provisions of this law.

The passage of the Fugitive Slave Act intensified tensions between the North and South and played a role in the lead up to the Civil War. It also sparked significant resistance and activism among abolitionists and supporters of the Underground Railroad, who worked to help fugitive slaves escape to freedom in Canada or other safe havens.

Overall, the Fugitive Slave Act of 1850 was a significant and contentious piece of legislation that highlighted the deep divisions over slavery in the United States during the mid-19th century.