Ah, thank you for the explanation of the specialist use of immunity in this context. That's a clever legalistic way to circumvent the idea of non-self-incrimination and/or a right-to-silence. So... I suppose the trick is for the state to pick on innocent/unprosecutable/unthreatening/&c acquaintances of the people the state wants to [attack in various unspecified ways that presumably don't include legal prosecution as the state clearly has no evidence of a convictable crime] and bully them into saying anything that might allow a (pretence of) reasonable cause to extend the bullying/witch-hunt/imprisonment-without-prosection to more targets. That's a helluva power to circumvent the more ordinary processes of criminal law and hypothetical human rights.

Apart from the famous case of McCarthyism that has lent its name to these sort of "witch-hunts", can anyone tell me if this sort of thing happens much?