The defendant by a plea becomes plaintiff.

Explanation

(English-origin maxim.) When a defendant interposes an affirmative plea, he takes on the burden of proving it — in that respect he becomes a plaintiff as to the matter pleaded.

Where this applies

• A defendant who raises an affirmative defense of fraud must now prove that fraud actually occurred — by pleading it, he takes on the burden of a plaintiff on that issue.
• A party who claims self-defense in an assault case must present evidence supporting that claim, because the affirmative plea shifts the burden of proof to him.
• A landlord who answers a tenant's lawsuit by asserting the tenant breached the lease first must prove that breach, because raising the plea makes the defendant a plaintiff on that point.