I'm a bit more cynical and was thinking of the military using it for interrogation, or worse police getting a warrant to put a hat on you that pulls the info.

MIT already has a device that scrapes your internal monolog by using sympathetic reflexes in the throat. Technologically speaking, the requirement for an implant is a current limitation that will be overcome.

So while legally questions about use are somewhat ambiguous, typically the solutions don't get resolved until someone decides to abuse it.