La. Roads, Bridges and Ferries § 48:1098
No member of the authority or officer or employee thereof shall, either directly or indirectly, be a party to or in any manner interested in any contract or agreement with the authority for any matter, cause or thing whatsoever by reason whereof any liability or indebtedness shall in any way be created against the authority. If any contract or agreement shall be made in violation of the provisions of this Section, the same shall be null and void, and no action shall be maintained thereon against such authority.
Nothing in this Part shall be construed to limit the power of the authority to construct, repair or improve any bridge or ferry or portion thereof, or any addition, betterment or extension thereto, directly by the officers, agents and employees of the authority, or by contract; nor shall this section apply to contracts for legal, engineering, auditing, accounting or other professional services.
La. Roads, Bridges and Ferries § 48:1098