From the Wall Street Journal:
Policy problems aside, by transforming the mandate into a tax to avoid one set of constitutional problems (Congress having exceeded its constitutionally enumerated powers), the court has created another problem. If the mandate is an indirect tax, as the Supreme Court held, then the Constitution’s “Uniformity Clause” (Article I, Section 8, Clause 1) requires the tax to “be uniform throughout the United States.” The Framers adopted this provision so that a group of dominant states could not shift the federal tax burden to the others. It was yet another constitutional device that was simultaneously designed to protect federalism and safeguard individual liberty.
The Supreme Court has rarely considered the Uniformity Clause’s reach, but it cannot be ignored. The court also refused to impose meaningful limits on Congress’s power to regulate interstate commerce for decades after the 1930s, until justices began to re-establish the constitutional balance in the 1990s with decisions leading up to the ObamaCare ruling this summer. And although the court has upheld as “uniform” taxes that affect states differently in practice, precedent makes clear that a permissible tax must “operate with the same force and effect in every place where the subject of it is found,” as held in the Head Money Cases (1884). The ObamaCare tax arguably does not meet this standard.