Under 12(h)(1), the Rule is saying that the 12(b)(2)-(5) defenses are either:
(1) waived if omitted from the first motion per 12(g)(2);
(2) waived if failed to make by motion under that rule; or
(3) waived if not included in a responsive pleading or amendment allowed by Rule 15(a)(1) as a matter of course -------
My issue here is I'm not quite where the "matter of course" is coming from. (I understand it's from 15(a)(1), just not sure why we would go there) From what I understood, to raise one of the 12(b) defenses, the party must file a motion prior to a responsive pleading. But, how can the 12(b)(2)-(5) defenses be in a responsive pleading, or an amendment as a matter of course, if the motion w/ defense was filed first?
Is this referring to if the plaintiff amended the complaint and then the defendant is responding to this amended complaint with a 12(b)(2)-(5) motion?
If not, would you be able to clarify how this situation would arise?
First, go back to the introductory language of 12(b): Defenses are to be asserted in the responsive pleading, but those seven defenses can be asserted by pre-answer motion. So you have your choice of how to raises one of those defenses.
Second, these defenses only will be asserted in a responsive pleading, obviously--you only raise defenses in response to a claim.
Third, a defending party can amend a responsive pleading and, under 15(a)(1), it might be as a matter of course, That's the significance of 15(a)(1)'s distinction between a pleading to which a responsive pleading is required in (B) and one to which a responsive pleading is not required in (A).
So where does that leave us? A disfavored defense is waived if either a motion or a responsive pleading is filed without one of those defenses--in other words, whatever the defendant files first, must include one of these defenses. But the rule goes one step further and allows a party to raise it in an amendment to that responsive pleading, provided it is one filed as a matter of course--that is, as allowed by FRCP 15(a)(1).
So imagine the following: Defendant answers and forgets to include a 12(b)(3) defense. Ten days after serving the answer, defendant realizes his mistake. Under FRCP 15(a)(1)(A), he had 21 days from serving his responsive pleading to amend as a matter of course; only 10 days have passed. So the defendant could file an amended answer as a matter of course, without seeking consent or leave. And under FRCP 12(h)(1)(B)(ii), the disfavored defense can be included, because this is an amended pleading as a matter of course.