Final answer:
The Fugitive Slave Act was controversial because it enforced slavery in free states, leading to increased federal power and tension between North and South.
Step-by-step explanation:
Controversial because it promoted slavery:
The Fugitive Slave Act was controversial because it promoted slavery in free states and required citizens to assist in the capture of escaped slaves. It also denied alleged fugitive slaves a jury trial or court testimony, contributing to the expansion of federal policing powers. This law compelled Northern officials and citizens to enforce slavery laws, contrary to their personal beliefs and state laws, leading to a rise in anti-slavery sentiment and conflict between the North and South.
Under the act, local authorities in the North had to cooperate with federal agents in apprehending fugitive slaves and individuals who refused to comply could face fines and imprisonment. This raised concerns among many Northerners about the expansion of federal power, the undermining of local and state laws, and the infringement on personal liberties.