Answers don't get much discussion in class-action strategy, because aside from making sure one's responses are accurate, what is there to say? There are only so many ways a party can say "Admit," "Deny," and "Don't know." The one place where the class-action answer can get tricky is in the assertion of affirmative defenses. What, you may be asking, can possibly go wrong there?

Well, take the case of Hofstetter v. Chase Home Finance, 2011 U.S. Dist. LEXIS 65764 (N.D. Cal. Jun. 21, 2011). The litigation involved the defendants' alleged practice of force-placing (buying for the borrower) required flood insurance in California.

Two months after the court certified a class (and eight months after the deadline for amending pleadings had passed), the defendants found out that some of the proposed class members were delinquent on their mortgage accounts, meaning that even if the defendants were liable to them the damages might be offset by the plaintiffs' own legitimate debts. So they sought leave to amend under Rule 15 to add two more affirmative defenses, setoff and recoupment. (For those keeping count, these were the defendants' 44th and 45th affirmative defenses.)

In addition to arguing the standard "Rule 15 allows liberal amendment" (undercut here by the deadline for amendments), the defendants also argued that they could not have included the two affirmative defenses until after certification because, while the defenses applied to some absent class members, they did not apply to the named plaintiff. Judge Alsup (yes, that Judge Alsup) was having none of their argument.

Although these defenses only became applicable after class certification, defendants were aware of the potential class since the complaint was filed. In March 2010, plaintiff filed a class action complaint ... It is inconceivable that defendants did not know that some unnamed members of the class might be delinquent on mortgage payments from the day the complaint was filed.

(Emphases in original.)

The takeaway from this case is pretty simple: assert every affirmative defense that might apply to a class member, even if it has nothing to do with the named plaintiff. There's little downside to doing so, and in a jurisdiction like the Northern District of California, there may be real consequences to not doing so.