The Fugitive Act was a controversial act that in retrospect affected all African-Americans, free, enslaved, northern or southern. The Act contained a provision for the return of any person held to service labor in one state who escaped to another. (Book) In other words, it allowed slaveholders to go to the north and bring back slaves to work on their plantations.
The potential effects it had on fugitive slaves, is that they were forced to work all over again and that their journey was a waste. Also they probably received cruel punishments,