In Caso v Miranda Sambursky Slone Sklarin Verveniotis LLP, 180 AD3d 611, 612-13 [1st Dept 2020], the court held that the attorney was not liable to his client for testimony of a witness at a deposition:
Plaintiff’s contention in this legal malpractice action is that Arenas should have been better “prepared” for his deposition in the underlying personal injury action, so he could “remember” the statements he made to the detective. Plaintiff claims that, had defendants not been negligent, there would have been a plaintiff’s verdict. He claims that Arenas’s testimony damaged his case and prevented him from prevailing.
“[M]ere speculation of a loss resulting from an attorney’s alleged omissions … is insufficient to sustain a claim” for legal malpractice” (Gallet, Dreyer & Berkey, LLP v. Basile, 141 A.D.3d 405, 405–406, 35 N.Y.S.3d 56 [1st Dept. 2016] [internal quotation marks omitted]; Geller v. Harris, 258 A.D.2d 421, 685 N.Y.S.2d 734 [1st Dept. 1999] ). Plaintiff’s assertion that, had Arenas been better prepared, the jury would have returned a favorable verdict is pure speculation (Rudolf v. Shayne, Dachs, Stanisci, Corker & Sauer, 8 N.Y.3d 438, 443, 835 N.Y.S.2d 534, 867 N.E.2d 385 ; Brookwood v. Alston & Bird, LLC, 146 A.D.3d 662, 49 N.Y.S.3d 10 [1st Dept. 2017]. Defendants met their burden of showing that plaintiff cannot establish causation, in that plaintiff cannot prove that it would have prevailed in the underlying action “but for” defendant’s alleged negligence in preparing Arenas for his deposition (see Rudolf v. Shayne, 8 N.Y.3d 438 at 442, 835 N.Y.S.2d 534, 867 N.E.2d 385).