[Hunter x Hunter] How does Chain Jail work?

So Chain jail is a power design to only work on the Phantom Troupe. That I get. But how does Chain Jail know if the target is a “Phantom Troupes” or not?

Like if someone pretends to part of the Phantom Troupes and
Kurapika fooled would chain jail still work?

What if Chain jail is use on someone who is a Phantom troupe but the user doesn’t know, would it still work?