He is defeated by the plea that the action have been assigned.

Explanation

(English-origin maxim.) A defendant is barred by a plea showing that the cause of action has been assigned to another — the original plaintiff, having transferred his right, can no longer maintain the suit.

Where this applies

• A creditor who assigned his debt to a collection agency cannot later sue the debtor himself — his right to bring the action was transferred along with the debt.
• An inventor who sold her patent rights to a corporation is defeated by the plea that she no longer owns the claim — the action belongs to whoever holds the patent now.
• A landlord who assigned a lease to a new owner cannot sue the tenant for back rent, because the right to collect was transferred with the assignment.