Pocket Immunity Law and Legal Definition

Pocket immunity is an informal immunity that arises by way of assurances or promises by prosecutors. The promise is made either orally or by letter to a potential grand jury witness that s/he will be immune from any prosecution based upon that testimony. Such decisions are made informally, outside the supervision of a court.

Pocket immunity is merely a prosecutor's promise, and is contractual in nature. If a petitioner believes that a prosecutor breached the contractual promise, s/he will have normal contractual remedies. An immunity agreement is contractual in nature and may be interpreted according to contract law principles. In People v. Pettiford, 2010 Mich. App. LEXIS 813 (Mich. Ct. App. May 6, 2010), it was held that pocket immunity is enforceable according to contract principles, and the parties have those rights and remedies outlined in the immunity contract.