La. Stat. tit. 45 § 1148
The resolution authorizing the issuance of bonds under this Part shall be published once in a newspaper published in the political subdivision, or if no newspaper is published therein, then in a newspaper published in the parish in which the political subdivision is located, or if no newspaper is published in such parish then in a newspaper published in an adjoining parish. For a period of thirty days from the date of each publication any person in interest shall have the right to contest the legality of the resolution and of the bonds to be issued pursuant thereto and of the security for such bonds and the franchise granted to the purchaser or purchasers at any sale held for the enforcement of such security. After the expiration of the thirty day period no one shall have any right of action to contest the validity of the bonds, pledge or franchise, and all such bonds, security and franchises shall be conclusively presumed to be legal, and no court shall thereafter have authority to inquire into such matters.
La. R.S. § 45:1148