While proximate cause is always an element of torts, we believe that the additional element of “but for” causation is unique to legal malpractice claims.  “An attorney’s conduct or inaction is the proximate cause of a plaintiff’s damages if “but for” the attorney’s negligence “the plaintiff would have succeeded on the merits of the underlying action” (AmBase Corp. v Davis Polk & Wardwell, 8 NY3d 428, 434, 866 NE2d 1033, 834 NYS2d 705 [2007]), or would not have sustained “actual and ascertainable” damages (Dombrowski, 19 NY3d at 350; Brooks v Lewin, 21 AD3d 731, 734, 800 NYS2d 695 [1st Dept 2005], lv denied 6 NY3d 713, 849 NE2d 972, 816 NYS2d 749 [2006]).

1934 Bedford, LLC v Gutman Weiss, P.C. 2023 NY Slip Op 04558 Decided on September 13, 2023 Appellate Division, Second Department illustrates how this can derail plaintiff’s case.

“Although leave to amend a pleading should be freely given in the absence of prejudice or surprise to the opposing party (see id.), a motion for leave to amend should be denied where the proposed amendment is palpably insufficient or patently devoid of merit (see Buccigrossi v Glatman, 214 AD3d 696; Silverman v Potruch & Daab, LLC, 142 AD3d 660, 661; Pedote v Kelly, 124 AD3d 855, 856; Lucido v Mancuso, 49 AD3d 220, 229). “A determination whether to grant such leave is within the Supreme Court’s broad discretion, and the exercise of that discretion will not be lightly disturbed” (Gitlin v Chirinkin, 60 AD3d 901, 902; see U.S. Bank N.A. v Cuesta, 208 AD3d 821, 822; Johnson v Ortiz Transp., LLC, 205 AD3d 696, 697).

Here, the Supreme Court providently exercised its discretion in denying that branch of the plaintiffs’ motion which was pursuant to CPLR 3025(b) for leave to amend the complaint, as the proposed amendment was palpably insufficient or patently without merit. The proposed amendment failed to sufficiently allege that “but for” the defendants’ alleged negligence, the plaintiffs “would not have incurred any damages” (Rudolf v Shayne, Dachs, Stanisci, Corker & Sauer, 8 NY3d 438, 442; see Nomura Asset Capital Corp. v Cadwalader, Wickersham & Taft LLP, 26 NY3d 40, 49-50; McCoy v Feinman, 99 NY2d 295, 301-302).”