U.S. Sup. Ct.
12-167
Federal Rule of Criminal Procedure 11 governs guilty pleas. Rule 11(c)(1) instructs that [t]he court must not participate in [plea] discussions, and Rule 11(h) states that a variance from the requirements of th[e] rule is harmless error if it does not affect substantial rights. Rule 52(a), which covers trial court errors generally, similarly prescribes: Any error . . . that does not affect substantial rights must be disregarded.