N.Y. LFN Law § 80.00

§ 80.00 Bond resolution, or note resolution or certificate, may\ncontain estoppel clause. The resolution of a finance board authorizing\nthe issuance of bonds or notes, or the certificate of a chief fiscal\nofficer authorizing the issuance of notes, may, in the discretion of the\nfinance board or such chief fiscal officer, as the case may be, contain\na statement that the validity of such bonds or notes or any bond\nanticipation notes issued in anticipation of the sale of such bonds may\nbe contested only if:\n 1. Such obligations are authorized for an object or purpose for which\nthe municipality, school district or district corporation is not\nauthorized to expend money, or\n 2. The provisions of law which should be complied with at the date of\nthe publication of such resolution or summary thereof, or certificate,\nas the case may be, are not substantially complied with, and an action,\nsuit or proceeding contesting such validity, is commenced within twenty\ndays after the date of such publication, or\n 3. Such obligations are authorized in violation of the provisions of\nthe constitution.\n