All courts agree that the proponent of an attorney-client privilege claim must carry the burden of proof (although courts disagree about whether that burden includes establishing the lack of a waiver). In contrast, most courts recognize a complicated shifting of burdens in the work product area.
In In re OM Group Securities Litigation, 226 F.R.D. 579, 584 (N.D. Ohio 2005), the court explained (as do most courts) that: (1) the party seeking an adversary’s work product must establish relevance; (2) the burden then shifts to the party withholding the work product to show that it meets the work product standards; (3) the burden then shifts back to the requesting party to show that it has “substantial need” of the materials and is unable to obtain the “substantial equivalent” without “undue hardship”; and (4) if the requesting party carries this burden, the court must nevertheless protect the protecting party’s lawyers’ and other representatives’ opinions.
This elaborately choreographed shifting of burdens back and forth highlights another important difference between the work product doctrine and the attorney-client privilege.