There can be no plea against an action which destroys the matter of the plea.

Explanation

(English-origin maxim.) A plea cannot stand when the action, if successful, would destroy the very matter pleaded — a defense that the action itself would eliminate is no defense at all.

Where this applies

• A borrower sues to void a mortgage, and the lender cannot use the mortgage as a defense because the lawsuit, if successful, would destroy the very document being pleaded.
• A plaintiff seeks to cancel an insurance policy obtained by fraud, and the insurer cannot plead the policy's limitation clause because the suit aims to destroy the policy itself.
• A party challenges the validity of an arbitration agreement, and the other side cannot compel arbitration under that agreement because the challenge, if successful, would eliminate it.