La. Stat. tit. 33 § 4260
For a period of sixty days from the date of the promulgation of the result of any election held hereunder, any person in interest may contest the legality of the election, after which time no one shall have any cause of action to contest the regularity, formality or legality of the election for any cause whatever, it shall be conclusively presumed that every legal requirement has been complied with, and no court shall have authority to inquire into such matters after the lapse of sixty days. The resolution authorizing the issuance of bonds shall be published once in a newspaper published in the municipality, or if no newspaper is published therein, then in a newspaper published in the parish in which the municipality is located, or if no newspaper is published in the parish then in a newspaper published in an adjoining parish. For a period of thirty days from the date of the publication any person in interest may contest the legality of the resolution and of the bonds to be issued pursuant thereto and the provisions securing the bonds. After the expiration of thirty days no one shall have any right of action to contest the validity of the bonds or the provisions of the resolution pursuant to which the bonds were issued, and all the bonds shall be conclusively presumed to be legal, and no court shall thereafter have authority to inquire into such matters.
La. R.S. § 33:4260