La. Stat. tit. 39 § 1126
For a period of sixty days from the date of the promulgation of the resolution issuing the bonds and pledging and dedicating the tax therefor, any person in interest may contest the legality of the bond issue provided for or the tax pledged and dedicated, for any cause; after which time no one shall have any cause or right of action to contest the legality, formality or regularity of the proceedings, tax provision or bond authorization, for any cause whatsoever. If the validity of any proceedings, tax provision or bond authorization, provided for under the provisions of this Chapter, are not raised within the sixty days, the authority to issue the bonds, the regularity thereof, and the taxes pledged and dedicated to provide for the payment of the principal and interest, shall be conclusively presumed and no court may inquire into such matters. If any resolution is adopted or proceedings had more than thirty days after the promulgation of the ordinance issuing the bonds and pledging and dedicating the tax, no contest, action or proceeding to question the validity or legality of the resolution or proceeding so adopted, shall be begun in any court by any person for any cause whatsoever after the expiration of thirty days from the date wherein the resolution was adopted or proceedings had.
La. R.S. § 39:1126