Having thought about this for a few days, I just want to very briefly say why I disagree with the Supreme Court's ObamaCare decision. This is not a legal brief, so a summary in plain English will suffice, focussing on the Chief Justice since his views prevailed.
Chief Justice Roberts was correct about the Commerce Clause. But I'm having a lot of difficulty accepting that he could have been correct about the "tax" issue. He said that it was not a "tax" for purposes of the Anti-Injunction Act (which requires a tax to be paid before a lawsuit is brought), but was a "tax" for purposes of the Constitution's Taxing Clause. The dissent responded: "That carries verbal wizardry too far, deep into the forbidden land of the sophists."
It is unlikely that the Congress that enacted the Anti-Injunction Act meant for the word "tax" to exclude any payment pursuant to the Tax Clause of the Constitution. So, Roberts apparently argues that the Congress that enacted ObamaCare impliedly amended the Anti-Injunction Act, by deliberately not calling the penalty a "tax." But there are many reasons why Congress would have refrained from using the word "tax," quite apart from amending the Anti-Injunction Act (e.g. the word "tax" is stigmatized, and Congress also wanted to rephrase this provision so it would sound more plausible as an exercise of the Commerce Clause power). It's a familiar rule of statutory construction that an earlier statute and a later statute should be interpreted, if possible, in a way that gives full effect to both of them, before concluding that the later statute amends the earlier one. Roberts wrote:
The Affordable Care Act does not require that the penalty for failing to comply with the individual mandate be treated as a tax for purposes of the Anti-Injunction Act.
True, but that requirement does not have to arise from the Affordable Care Act. It can instead arise from the Anti-Injunction Act.
Roberts should have voted to dismiss the case for lack of jurisdiction, given his belief that the Taxing Clause rather than the Commerce Clause legitimized the payment required by ObamaCare. The decision of the Eleventh Circuit would then have been undisturbed (given the 4-4 SCOTUS split on the merits).
So basically I think there was a mistake of statutory construction. Not deliberate, of course --- though perhaps influenced by a desire to avoid deadlock. Deadlock and gridlock and circuit splits are not so horrible that they justify verbal wizardry, although a chief justice would understandably be very eager to avoid them.
Incidentally, Judge Kavanaugh of the D.C. Circuit supported dismissal for lack of jurisdiction, and so did the Fourth Circuit. That route would have also served another principle of statutory construction: avoiding constitutional rulings.
UPDATE (July 4): John Hinderaker over at Powerline has a good post documenting that Democratic members of Congress maintained that the Tax Clause helped justify the individual mandate penalty. But even assuming (as C.J. Roberts does) that Congress suggested the opposite, there's a big difference between suggesting that the penalty is not a tax, versus amending the Anti-Injunction Act.
Did the Congress that enacted the Anti-Injunction Act mean for the word "tax" to include all payments pursuant to the Tax Clause of the Constitution, except where a later Congress incorrectly suggests that the payment is not pursuant to the Tax Clause of the Constitution? Or except where a later Congress chooses to use a label other than the word "tax"? I disagree with those exceptions, but it's a close question, and the Chief Justice's conclusion is not blatantly wrong like a lot of other SCOTUS decisions have been.