La. Stat. tit. 33 § 140.50.21
After the adoption of a master plan, in whole or in part, as provided in R.S. 33:140.50.16, the municipality or parish or other public body shall not accept, lay out, open, improve, grade, pave, or light any street within the area covered by the adopted plan, in conflict with the plan unless such street has been accepted or opened as, or has otherwise received the legal status of, a public street prior to the adoption of a master plan, or unless such street corresponds in its location and lines with a street shown on a subdivision plat approved by such commission or on a street plat made by and adopted by such commission. However, the town council or, in the case of a street outside of the municipality, the police jury may locate and construct or may accept any other street if the ordinance or other measure for such location and construction or for such acceptance be first submitted to such commission for its approval, and if disapproved by the commission, be passed by not less than two-thirds of the entire membership of the town council or police jury, as appropriate. A street approved by the commission upon such submission, or constructed or accepted by such two-thirds vote after disapproval by the commission, shall have the status of an approved street as fully as though it has been originally shown on a subdivision plat approved by the commission or on a plat made and adopted by the commission.
La. R.S. § 33:140.50.21