La. Revenue and Taxation § 47:299
It is the intention of the legislature in enacting this Part to recognize the most universally accepted method of determining taxable income and to provide a simple method by which an individual subject to the income tax laws of the state of Louisiana may determine the amount of tax due with minimum effort and expense. If any provision of this Part, or the application thereof to any person or circumstance is held invalid under the constitution of the state of Louisiana or of the United States, the remainder of the Part shall cease to be effective for any taxable year ending after judgment of the court of last resort becomes final, and the provision of Part I and Part II of this Chapter relating to individual taxpayers shall become fully effective with respect to any such year.
La. Revenue and Taxation § 47:299