In pleading to a preceding pleading, a party shall set forth affirmatively accord and satisfaction, arbitration and award, assumption of risk, contributory negligence, discharge in bankruptcy, duress, estoppel, failure of consideration, fraud, illegality, injury by fellow servant, laches, license, payment, release,
res judicata, statute of frauds, statute of limitations, waiver, and any other matter
constituting an avoidance or affirmative defense.
Duplicate litigation
is to
be avoided and thus the legal concept of
res judicata - when a court has decided the legal issue already it
constitutes a bar to a subsequent action involving the same claim.