Mind-Reading Jack can kind of turn this power on and off. As it's hard for him he usually can read anybodies minds unless it's another mind reader for some reason it gets jumbled and will sound weird when he tries to listen to other mind readers thoughts. He isn't able to read the minds of individuals who are as strong willed as him.
Telepathy Jack is only able to use his telepathy powers if the individual is usually younger then 15 or allowing him to have this permission into their mind. Other then that he isn't able to get into a mind of somebody unless they're off guard about him or relaxed. Though they can try and fight against him which depending on his days somebody can close him out.