Equitable Estoppel is a principal which comes into play most often when a case is not commenced within the statute of limitations. The theory is that plaintiff was lulled into not starting the case by a wrongful act of defendant. Considering that blown statutes of limitations are one well recognized basis for legal malpractice cases, the two concepts are suitably intertwined.

In a legal malpractice decision (arising from a medical malpractice case) we see Justice Shulman of Supreme Court, New York County writing:

"The doctrine of equitable estoppel may bar a defendant from asserting the statute of limitations when the plaintiff "was induced by fraud, misrepresentations or deception to refrain from filing a timely action" (Ross v Louise Wise Sews., Inc., 8 NY3d 478, 491 [2007], quoting Simcuski v Saeli, 44 NY2d 442, 448-449 [1978]; General Stencils, lnc. v Chiappa, 18 NY2d 125, 128 [ 19661). Equitable estoppel will "bar the assertion of the affirmative defense of the Statute of Limitations where it is the defendant’s affirmative wrongdoing . . . which produced the long delay between the accrual of the cause of action and the institution of the legal proceeding" (Zumpano v. Quinn, 6 NY3d 666, 673 [2006], quoting General Stencils, lnc. v Chiappa, 18 NY2d at 128). A defendant may be precluded from.invoking a statute of limitations defense under such circumstances (Putter v North Shore Univ. Hosp., 7 NY3d 548, 552 [ZOOS], quoting Zumpano v Quinn, 6 NY3d at 673).
Where a medical malpractice claim is asserted, the patient’s medical records are material to reaching a responsible decision on whether there are grounds for a lawsuit and equitable estoppel may arise where there is an unreasonable delay in delivering records to an attorney consulted in a suspected case of malpractice (Karnruddin v Desrnond, 293 AD2d 714 [2d Dept 20021). Concealment by a physician or failure to disclose his own malpractice may, in a proper case in conjunction with other factors, provide a foundation for seeking to invoke the doctrine of equitable estoppel to extend the applicable period of limitations (Simcuski v Saeli, 44 NY2d at 452).

Of critical importance, due diligence on the plaintiffs part in ascertaining the facts and commencing the action is an essential element when plaintiff seeks to invoke this doctrine. Although there are exceptions, "the question of whether a defendant should be equitably estopped is generally a question of fact” (Putter v North Shore Univ. Hosp., 7 NY3d at 553). On the other hand, where plaintiff is timely aware of the facts requiring him to make further inquiry before the statute of limitations expires, an equitable estoppel defense to the statute of limitations is inappropriate as a matter of law (Pahlad w Brustman, 8 NY3d 901 [2007])."InLopresti v Bamundo, Zwal & Schermerhorn, LLP; 2010 NY Slip Op 33436(U);  Sup Ct, NY County ; Docket Number: 100206/09; Judge Martin Shulman determines that equitable estoppel does not apply."This record contains no evidence of any affirmative wrongdoing or purposeful concealment on Dr. Marino’s part caused Lopresti’s delay in commencing the underlying action (see Zumpano v Quinn, 6 NY3d at 673; Kamruddin v Desmond, 293 AD2d at 71 5). Lopresti’s allegedly incorrect statements to Bamundo ZwaI as to the last date Dr. Marino treated Vito Lopresti and the delay in having a personal representative appointed cannot be held against Dr. Marino. Rather, Lopresti’s and/or Bamundo Zwal’s own inaction caused the untimely commencement of the underlying case. See, e.g., Public Adm’r of State of New York v Beth Israel Med. Ctr., 2007 WL 176380 (Sup Ct, NY County, Carey, J)(granting summary judgment dismissing action as time barred and finding that hospital should not be equitably estopped from asserting statute of limitations as a defense where plaintiffs inaction and failure to avail itself of various procedural safeguards’ prevented timely commencement of action)."