1) What we tried to identify with both time periods in FRCP 15(a)(1) is when the window opens (earliest the party can amend as a matter of course) and when the window closes (party no longer can amend as a matter of course). The party can amend at any time within that window. So a plaintiff who wants to amend the complaint can do so at any time from right after filing the original through service of the original through service of the response through 21 more days. She not wait until the response is filed (although in practice she might, because she does not know of the defects until the response comes). If she identifies defects herself, she need not wait for anything.
2) Someone asked the following question outside of class: Which FRCP 15(a)(1) time period applies to an Answer with a counterclaim? Is it (B), because the counterclaim makes this a pleading to which a responsive pleading is required? Or do we divide the pleading up--(A) controls the parts that do not require a responsive pleading (e.g., the answers to the allegations) and (B) controls the parts that do require a responsive pleading (e.g., the counterclaim).
I took the question to a Civ Pro Prof Listserv (that is a group that knows how to party). Most said the textual argument is (B) controls all, since the "pleading" means the entire document, which is one to which a responsive pleading is required because of the counterclaim.
3) One person responded with the following, which I think illustrates something about both of the above points. And it shows how much of what happens in litigation occurs in the shadow of the rules but plays out in very practical terms . And it shows how the judge enforces cooperation and practical action within the litigation:
This actually happened to me, sorta. I filed an answer and a counterclaim and the next day I noticed that I had left off an exhibit relevant to the counterclaim so (this was in the days of paper filing) I walked over to the clerk’s office and I got the same clerk. We were on friendly terms because I liked to file stuff myself. The federal courthouse was right across the street and I liked the fresh air (and didn’t bill anyone for the time it took). She said “why are you back again?” I sheepishly explained what had happened. She said “hold on, it was late yesterday and I didn’t have time to put it in the file,” so she took the missing exhibit stapled it to my first filing and put it in the file. I hustled back to the office and snatched the amended answer/counterclaim that I was serving by mail out of the outgoing mail before it had been picked up.
My thought process was that since the other side was going to have to answer the counterclaim I had a freebie coming. I didn’t give any thought to whether the fact that the exhibit was only relevant to the counterclaim made any difference or not. I suppose I’d read the rule that the freebie would only apply to the counterclaim.
But realistically, nobody would have made an issue out of it. My plan had been to call opposing counsel and tell them to ignore the original and just deal with the amended one. The chances of them making a motion saying I needed permission from them or the court were vanishingly small and even if they did the judge would’ve looked at them cross-eyed and granted me permission to file an amended answer/counterclaim.
So I think that’s probably the closest to a real world answer. But good on your student for reading the rule carefully enough spot an at least potential ambiguity.