collateral attack
collateral attack. An attack on a judgment in a proceeding other than a direct appeal; esp., an attempt to undermine a judgment through a judicial proceeding in which the ground of the proceeding (or a defense in the proceeding) is that the judgment is ineffective. • A petition for a writ of habeas corpus is one type of collateral attack. — Also termed indirect attack. Cf. DIRECT ATTACK(1). [Cases: Judgment 470–523. C.J.S. Judgments §§ 499–533.]