I don't want to cause trouble, but there is a development that is endangering the way that defendant's plead their affirmative defenses. Now, many affirmative defenses result from a cut and paste of every defense raised in other answers. No more, at least according to a 2012 Houston case, Vargas v. HWC General Maintenance, LLC. The opinion briskly sets out the facts: it is an FLSA lawsuit with defendant raising numerous defenses but in legal conclusions without alleging a factial basis (such as alleging that the plaintiff was exempt from the FLSA but without explaining why or how). The legal issue according to the court: Do SCOTUS decisions requiring a plaintiff to plead a plausible claim, with supporting facts, or face dismissal under Rule 12(b)(6), apply to affirmative defenses? The court said, "yes" and dismissed twenty-three defenses (without prejudice to re-pleading to satisfy the federal pleading requirement). What's good for the goose is good for the gander.