Grand jury
A body of (often 23) people who are chosen to sit permanently for at least a month or year who decide whether to issue indictments
Probable cause
A reasonable ground to suspect that a person has committed a crime or that a place contains specific items connected with a crime. Under Fourth Amendment which amounts to more than a bare suspension but less than evidence that would justify a conviction
Immunity
Any exemption from a duty, liability or service of process
Discovery
The act of finding or learning something that was previously unknown