Equality, consistency, and impartiality in tax legislation

The ideal of equality can be conceived in law in a formal as well as in a substantive way. Contrary to what some authors suppose, the principle of formal equality is not entirely meaningless. It generates standards for treatment, i.e., for legitimate discriminations in law. The principle is like a sequence: it provides a kind of continuity in law-making: the past of the law should be consolidated in actual decisions and regulations. The principle of formal equality guides future decisions on standards for treatment, because they have to be compatible with decisions on legitimate discriminations and distinguishing features in the past. Therefore, consistency is required with the substantive judgments about relevant characteristics which underly the principle of (formal) equality. As for tax legislation, a consistent (and impartial) legislative classification is one which includes all persons who are similarly situated with respect to the purpose of the law. Especially, instrumentalist tax legislation runs the risk of unjustified discriminations. Under-inclusive classifications need an objective and reasonable justification: a legitimate aim, and proportionality between means and aim. Naked preferences, a special form of under-inclusive classification, may be due to a lack of impartiality on the part of the legislature. Instrumentalist tax expenditures constitute naked preferences if they are solely a response to private or interest group pressures. While recognizing the margin of appreciation of the legislature, the courts should more strictly scrutinize the proportionality involved in these cases. In this way, the courts can guarantee a certain degree of consistency in legislation (besides consistency in the application of the law). They protect the taxpayer against naked preferences of the legislative majority