The attorney-client privilege protects communications -- rather than historical facts, the circumstances of attorney-client relationships or communications, etc. This basic principle often precludes deponents from citing the privilege in refusing to answer "yes" or "no" questions.
In Montauk U.S.A., LLC v. 148 South Emerson Associates, LLC, the court explained that "questions pertaining to the existence of [privileged] communications generally are not covered by the privilege." No. CV 17-4747 (SJF) (AKT), 2019 U.S. Dist. LEXIS 9339, at *8 (E.D.N.Y. Jan. 17, 2019). The court specifically dealt with questions plaintiffs' lawyer posed to third party witnesses, such as asking a deponent "Did you sign a retainer agreement . . . ?"; "Have you paid fees for this case?"; "Have you seen a bill in this case?" Id. at *10. The court held that defendants' lawyer had improperly directed the witness "not to answer the questions regarding whether he had signed a retainer agreement and whether he had paid fees for this case." Id. at *10-11. As the court noted, "[t]he questions called for a simple 'yes' or 'no' answer and the responses would have revealed only facts." Id. at *11.
The court's holding might have been different if the deposition questions had implicitly sought disclosure of privileged communications – such as asking "yes" or "no" questions about protected communications on some very specific topics. But lawyers should always remember that the privilege protects communications rather than historical facts or events.