If a witness simply forgets something during a deposition, but the information is available in a document, may the witness refresh his memory by reviewing the document? This topic was debated in Walker v. City of N. Las Vegas, where the designee was asked to testify about the provisions of certain search warrants executed in the City. Plaintiff contended the designee was unprepared, the court decided he was.
The court first noted “Rule 30(b)(6) is not designed to be a memory contest, especially if the witness is requested to prepare to testify as to hundreds of specific occurrences at which he or she may not have been present.” Even after “reviewing hundreds of reports and related documents prior to a deposition, review of particular documents at a deposition to refresh the witness’ memory as to a specific occurrence may be necessary.” A large amount of time might be required “to review a large volume of police reports during a deposition” However, “Plaintiffs’ counsel should have permitted the witness to review the police report about which he was being questioned, in the spirit of cooperation and for purposes of forming the record pertaining to that police report.”
I suspect this logic is not merely limited to 30(b)(6) designees. I doubt a witness will lose much credibility with a jury if opposing counsel refused to provide the witness with the document about which he was being questioned.
 No. 2:14-cv-01475, 2017 U.S. Dist. LEXIS 165861, 2017 WL 4467538 (D. Nev. Oct. 5, 2017).