What a difference a little bit of homework can make.
At the risk of redundancy (see, e.g., "Why It's So Important to Invetigate Your Child's Negligence Claim BEFORE You File Suit in NY"), if you fail to investigate the circumstances surrounding a personal injury action in New York before you file your initial legal papers - particularly a Notice of Claim against the City of New York or another quasi-governmental municipality - you do so at your own peril.
Consider the Manhattan slip and fall case of Mongelluzzo v. City of New York. In that case, the plaintiff sustained serious injuries to her ankle when she slipped and fell on a patch of ice that formed from water that had pooled in defective patch of New York City sidewalk over time. But that's not what the plaintiff's initial Notice of Claim said; rather, it merely asserted that she had slipped on "a piece of ice negligently allowed to remain on said sidewalk."
Recognizing belatedly - and well after the time within which the Notice of Claim was to be served - that this theory alone was likely insufficient to pin liability on the City, the plaintif sought to amend her Notice of Claim, contending that she had slipped and fallen on "ice negligently allowed to remain on said sidewalk and which was formed when water pooled in a crack in the sidewalk of which the City had prior written notice."
The Court didn't buy it. And here's why:
""General Municipal Law Section 50-e(6) notice of claim amendment provision merely permits correction of good faith, non-prejudicial, technical mistakes, defects or omissions, not substantive changes in the theory of liability." See Mahase v. Manhattan & Bronx Surface Tr. Operating Auth., 3 A.D.3d 410 (lst Dept 2004). "Any amendment that creates a new theory of liability is not within [GML 50-e(6)]'s purview."