La. Stat. tit. 33 § 4160.33
No contest or proceedings to question the validity or legality of any resolutions or ordinances adopted or proceedings undertaken under the provisions of this Chapter shall be initiated in any court by any person for any cause whatsoever after the expiration of thirty days from the date when the resolution, ordinance, or proceeding was published, and after such time the regularity of such resolution, ordinance, or proceeding shall be conclusively presumed. If the validity of any certificates issued under the provisions of this Chapter is not raised within thirty days from date of publication of the resolution or ordinance issuing said certificates, the legality thereof and the legality of the local or special assessments necessary to pay the same shall be conclusively presumed, and no court shall thereafter have authority to inquire into such matters.
La. R.S. § 33:4160.33