Why was it easy to make a free black a slave under the fugitive slave law?

Under the Fugitive Slave Law, it was easy to make a free black a slave because the law required individuals to cooperate in capturing and returning alleged fugitive slaves, often leading to false accusations and kidnappings of free black individuals who were then wrongfully enslaved. The law had very limited due process protections for alleged fugitive slaves, making it easier for slaveowners to exploit the system and claim free black individuals as their property.