In the context of contract law, debt collection and civil litigation, the term judgment proof is commonly used to refer to defendants or potential defendants who are financially insolvent, or whose income and assets cannot be obtained in satisfaction of a judgment.
If sued, the defendant cannot claim being "judgment proof" as an affirmative defense.
If a plaintiff were to secure a legal judgment against an insolvent defendant, the defendant's lack of funds would make the satisfaction of that judgment difficult, if not impossible, to secure.
[1] In some jurisdictions, some classes of income and assets are exempt from being accessed to pay a judgment.
[2] The cost of collecting a judgment may also contribute to an assessment of whether a debtor is judgment-proof.