La. Stat. tit. 38 § 3085.6
For a period of thirty days after the date of publication of the resolution authorizing the issuance of bonds hereunder, any persons in interest shall have the right to contest the legality of the resolution and the legality of the bond issue for any cause. After this time no one shall have any cause or right of action to contest the legality of the resolution or of the bonds authorized thereby for any cause whatsoever. If no suit, action, or proceeding is begun contesting the validity of the bond issue within this thirty day period, the authority to issue the bonds and to provide for their security and payment in the matter provided in the resolution, the legality thereof and of all of the provisions of the resolution authorizing the issuance of the bonds shall be conclusively presumed, and no court shall have authority to inquire into such matters.
La. R.S. § 38:3085.6