Under the Federal Rules and parallel state rules, litigants may use what are called "contention interrogatories" to explore adversaries' factual support for their legal contentions. Courts normally regulate the timing of those, generally prohibiting litigants from using that tactic too early in the discovery process. This timing issue highlights the "intensely practical" nature of the work product doctrine — in contrast to the more abstract and absolute attorney-client privilege.

In Lawrence v. Schlumberger Technology Corp., Case No. 1:14-cv-00524 JLT, 2015 U.S. Dist. LEXIS 78024, at *3-6 (E.D. Cal. June 16, 2015), plaintiff submitted contention interrogatories asking defendant to "state all facts" on which the defendant based certain employee classifications pursuant to the California Labor Code and other regulations. The court agreed with defendant that "the interrogatory may invade the attorney work product privilege" — noting that "[h]ad Plaintiff not intended to invade this privilege, he would not have referenced California law or the Wage Orders." Id. at *11. But the court concluded that "when the objectionable material is carved away, there remains a permissible question." Id. at *14. The court therefore ordered defendant to provide the facts underlying its employee classification of plaintiff's job position (with no reference to the law).

Although litigants ultimately must explain the factual basis for their legal contentions, they should be on the lookout for contention interrogatories that impermissibly seek their work product before applicable rules, court orders, or the trial process require the disclosure.