The Supreme Court on Thursday upheld a provision of the Trump tax cuts that taxed American shareholders of U.S.-controlled foreign companies on otherwise untaxed company earnings. The case, Moore v. United States, generated interest for the potential implications it would have for a wealth tax — specifically, one based on taxing investment gains that have not yet been realized. Ultimately, the Supreme Court punted on this question, describing its decision as “narrow” and “limited.” The majority opinion by Justice Brett Kavanaugh neither opened the door for such a wealth tax nor slammed it shut. The concurring and dissenting opinions, however, made it clear that there are at least four votes among the conservative justices to constitutionally limit taxes to income that has been realized.

However the justices might ultimately rule on such a matter, it doesn’t change the fact that the idea of taxing unrealized gains is a bad one that should be rejected on the merits.