This issue came up in the review session (I'm afraid I'm not quite sure who brought it up): When is a Twombly-Iqbal (Twiqbal) defense waived by failing to mention it in a timely fashion? Consider the following two scenarios.
Scenario One: P sues D in federal court. D brings a motion to dismiss for lack of personal jurisdiction, which the court denies. D then brings a motion for more definite statement, on the grounds that the pleading standards in Twombly and Iqbal (Twiqbal) have not been satisfied. Is the defense waived by failing to bring it up in the first motion?
Scenario Two: P sues D in federal court. D answers the complaint, without introducing the objection that the standards in Twiqbal have not been satisfied. Later D brings up the Twiqbal defense, perhaps in conjunction with a motion for more definite statement. Is the defense waived?
If one considers the Twiqbal defense to be, or to be analogous to, a motion to dismiss for failure to state a claim, then it should not be waived in either scenario. The defense of failure to state a claim can be brought up at any time. The only exception is that the defense is generally considered waived if it is brought up for the first time on appeal. (In addition, if one fails to bring up failure to state a claim in one's first preanswer motion, and the defense was available at the time of that motion, one cannot bring it up in a second preanswer motion. But that is no great loss, because one can bring it up in one's answer or later in a motion for a judgment on the pleadings.)
In Twombly the Twiqbal defense was indeed characterized as failure to state a claim. But in Iqbal the court made clear that the standards in Twiqbal come from the pleading requirements in FRCP 8(a), not from the demands of stating a claim. One might state a claim and nonetheless be insufficiently specific to satisfy Twiqbal and FRCP 8(a).
So understood, the Twiqbal defense would be waived in Scenario Two, although not Scenario One. Answering the complaint waives any argument that the pleading standards in FRCP 8(a) were not satisfied I cannot find a court saying as much, but that is what courts have concluded with respect to the defense that the pleading standards in FRCP 9(b) having not been satisfied. U.S. ex rel. Lam v. Tenet Healthcare Corp., 481 F.Supp.2d 689 (W.D. Tex. 2007); Todaro v. Orbit Intern. Travel, Ltd., 755 F.Supp. 1229 (S.D.N.Y. 1991).
There’s even an argument that the Twiqbal defense is waived in Scenario One. Under FRCP 12(g), “a party that makes a motion under [Rule 12] must not make another motion under this rule raising a defense or objection that was available to the party but omitted from its earlier motion.” The only exceptions identified are those in 12(h)(2) (which concerns failure to state a claim and failure to join a necessary party) and 12(h)(3) (which concerns lack of subject-matter jurisdiction). On this argument, Twiqbal should be treated like the other waivable defenses in FRCP 12(b)(2)-(5) (personal jurisdiction, venue, service, process). The Twiqbal defense was available when D made his first motion for lack of personal jurisdiction and is therefore waived.