La. Stat. tit. 19 § 115
In any case where a municipal corporation has actually, in good faith believing it had authority to do so, taken possession of privately owned, immovable property of another, and constructed facilities upon, under or over such property with the consent or acquiescence of the owner of the property, such owner shall be deemed to have waived his right to contest the necessity for the taking and to receive just compensation prior to the taking, but he shall be entitled to bring an action for such compensation, to be determined in accordance with the provisions of Section 110 of this Title, for the taking of his property or interest therein, the just compensation to be determined as of the time of the taking of the property, or right or interest therein, and such action shall proceed as if the municipal corporation had filed a petition for expropriation as provided for in Section 103 of this Title.
La. R.S. § 19:115