Hi, you've asked an incomplete question. However, I inferred you want to know the effect of the Fugitive Slave Acts.
Answer:
some free blacks were illegally sold into slavery
Step-by-step explanation:
These series of modified laws often created the opportunity for some to deliberately capture free black men, with false accusations that they were slaves running toward Canada. Which in reality wasn't the case, but they were mere victims of "kidnapping".
For example, the consequence of this law proved through in the case of Solomon Northup, who was captured under the disguised that he was a runaway slave until he regained his freedom after 12 years of slavery.