Martin Assoc., Inc. v Illinois Natl. Ins. Co. 2020 NY Slip Op 06860 [188 AD3d 572] November 19, 2020 Appellate Division, First Department is an excellent example of how the “but for” principle is applied.  In this case, the claim was that defendant attorneys failed to notify the excess carrier, and thus, coverage was lost.

“The court also properly dismissed the legal malpractice claim against Rubin. The duty to provide timely notice to the excess insurance carrier had long since expired when Rubin was retained in December of 2009. Thus, plaintiff cannot establish the element of proximate causation necessary to proving its legal malpractice claim, because it cannot show that if Rubin had provided notice to the excess carrier when it was retained, the carrier would not have denied coverage (see Reibman v Senie, 302 AD2d 290 [1st Dept 2003]). Nor did Rubin have the obligation to advise plaintiff of all potential malpractice claims against predecessor counsel when it was beyond the scope of its retention (see Keld v Giddins Claman, LLP, 170 AD3d 589 [1st Dept 2019]).”