Basically a slavery contract is a long-term and sometimes unfair agreement, which is signed by kpop artists with their management agencies. Some people say that slave contract sometimes takes away most of people's ability, for example whenever the trainee, for being an idol, wants to make a call home he must first check with his agencies and sometimes he can contact them but most of the time they can't because they aren't allowed to use anything. Furthermore, the agency or entertainment would make their employees work really hard to the point of exhaustion and would also undergo very intense training. There would be no way out of their contract anyway unless they file a lawsuit, like Kris and Luhan, or wait until the contract expires. Sometimes a contract lasts for years until that person is able to renew it with that company or doesn't sign with them again and joins other agencies or doesn't join at all. There are no really good outcomes when joining specific agencies because some of them would be unfair and treat you like you're not even human. They are essentially destroying their human rights and taking control over that person, forcing them to do whatever the CEO likes and not giving them any profit. For example SM and all the things that are happening around the world