Section 3A. In applying the laws referred to in section 2, the commissioner may, in his discretion, disallow the asserted tax consequences of a transaction by asserting the application of the sham transaction doctrine or any other related tax doctrine, in which case the taxpayer shall have the burden of demonstrating by clear and convincing evidence as determined by the commissioner that the transaction possessed both: (i) a valid, good-faith business purpose other than tax avoidance; and (ii) economic substance apart from the asserted tax benefit. In all such cases, the taxpayer shall also have the burden of demonstrating by clear and convincing evidence as determined by the commissioner that the asserted nontax business purpose is commensurate with the tax benefit claimed. Nothing in this section shall be construed to limit or negate the commissioner’s authority to make tax adjustments as otherwise permitted by law.