There are two instances in New York law where an expert might be necessary in legal malpractice litigation.  One is at the trial of the matter, and the other at a motion for summary judgment.  In general, an expert is necessary in any litigation where the "issues in this case are not part of an ordinary person’s daily experience."

In Suppiah v Kalish , 2010 NY Slip Op 06540 , Decided on September 7, 2010 , Appellate Division, First Department  defendant moved for summary judgment and plaintiff opposed the motion with the affidavit of an expert and some other affidavits.  The case was about immigration law legal malpractice. 
 

"According to plaintiff, he informed WFI that he was interested in gaining employment elsewhere. He also maintains that WFI refused to provide him with his original H1-B visa approval notice and other documents, which were in WFI’s exclusive possession and were necessary for him to prove his immigration status to prospective employers. Then, plaintiff claims, WFI retaliated against him by "benching" him, i.e., refusing to assign him any more work. Plaintiff alleges that the benching caused him to violate his visa, which required him to work to maintain his legal immigration status. WFI denies that it benched plaintiff and claims that it terminated him for legitimate business reasons. In December 2000, plaintiff resumed working for WFI. Plaintiff claims that the benching ended because he made clear his desire to continue working for WFI. WFI asserts that it simply decided to rehire plaintiff.

In May 2002, with the expiration date of his H1-B visa approaching, plaintiff asked defendant to take steps to ensure his continued legal status. Instead of petitioning for an extension of plaintiff’s existing H1-B visa, which he had done previously, defendant filed a petition for a new H1-B visa."
 

"The IAS court granted defendant’s motion and dismissed the complaint. The court did not expressly address plaintiff’s position that defendant did not establish his prima facie entitlement to summary judgment. However, it did find that plaintiff failed to raise an issue of fact regarding his claim that defendant committed malpractice.

We reverse because defendant failed to satisfy his prima facie burden of establishing entitlement to judgment as a matter of law. The issues in this case are not part of an ordinary person’s daily experience, and to prevail at trial, plaintiff will be required to establish by expert testimony that defendant failed to perform in a professionally competent manner (see Gertler v [*3]Sol Masch & Co., 40 AD3d 282 [2007]; Merlin Biomed Asset Mgt., LLC v Wolf Block Schorr & Solis-Cohen LLP, 23 AD3d 243 [2005]). As this is a motion for summary judgment, the burden rests on the moving party – here, defendant – to establish through expert opinion that he did not perform below the ordinary reasonable skill and care possessed by an average member of the legal community (see R.A.B. Contrs. v Stillman, 299 AD2d 165 [2002]; Estate of Nevelson v Carro, Spanbock, Kaster & Cuiffo, 259 AD2d 282, 284 [1999]). Also, defendant was required, on this motion, to establish through an expert’s affidavit that even if he did commit malpractice, his actions were not the proximate cause of plaintiff’s loss (see Tran Han Ho v Brackley, 69 AD3d 533 [2010]). By failing to submit the affidavit of an expert, defendant never shifted the burden to plaintiff. "