With the Supreme Court upholding the Affordable Care Act (popularly known as ‘Obamacare’) last week, here are five developments that caught onlookers, including the Court’s most prominent observers, by surprise.

The individual mandate is constitutional—as a tax

Before oral arguments in March, most constitutional scholars predicted that the Supreme Court would uphold healthcare reform as permissible under the Commerce Clause of the Constitution.  They relied on Wickard v. Filburn, a landmark Supreme Court case that held Congress has the power to regulate any activity (in this case, the production of wheat for personal use) so long as it affects interstate commerce.  During oral arguments, however, perceptions began to change and a majority of Supreme Court watchers, including former Court clerks, concluded that the Court would find the individual mandate unconstitutional as regulating inactivity as opposed to activity.

As it turns out, almost everyone was wrong.  Chief Justice Roberts and the Court’s conservative bloc did find that the Commerce Clause doesn’t cover regulation of inactivity. Instead, Roberts sided with the liberals and found the individual mandate to be a penalty-cum-tax—and therefore constitutional under the Tax Clause.

This surprised almost everyone, including the New Yorker’s Jeffrey Toobin, a leading Court authority, who had declared the individual mandate practically dead, as well as the prognosticators on intrade.com, who had rated the Court’s chances of overturning healthcare reform at over 75 percent.

Chief Justice Roberts is the swing vote

The most common scenarios discussed before the healthcare decision came out were as follows: (A) healthcare reform is overturned, 5-4, with the Court’s Republican appointees (Roberts, Alito, Kennedy, Scalia, Thomas) outvoting the Court’s Democratic appointees (Breyer, Ginsberg, Kagan, Sotomayor). (B) Healthcare reform is upheld by a 6-3 ‘unity’ vote, with Roberts and Kennedy, the traditional swing vote, siding with the liberals. (C) Healthcare reform is upheld with the votes of Kennedy and the liberals.

The first outcome was the most widely anticipated, and recent reports indicate that Roberts had originally sided with the conservatives, only to switch his vote during deliberations.

Liberals oppose Medicaid requirement

While the healthcare decision was welcome news for the White House, the administration didn’t get everything it wanted. Justices Kagan and Breyer sided with the Court’s conservatives in saying that the Medicaid expansion called for in the healthcare law couldn’t penalize states that refuse to expand their rolls by withholding federal funding.  This provision is too coercive to amount to a real choice for the states, the justices said, and exceeded Congress’ authority.

Supporters of the healthcare law will have to find a way to work around this change, as they anticipated it would add about 15 million Americans to the ranks of the insured. Some say it is not a big issue, however, as the increase in federal funding—90 to 100 percent of the costs in the next decade—will be too hard for the states to turn down.

In losing, conservatives may have won

While Obamacare stands, many conservatives see a silver lining in the Court’s ruling, and some liberals are fretting its long-lasting effects.

The Court’s limited view of the Commerce Clause–that it permits regulation of activity but not inactivity–has the potential to substantially limit the federal government’s regulatory powers in the future.

Kennedy a conservative trooper

The conservative justice that conservatives love to hate—Anthony Kennedy—surprised them this time around. Kennedy, who has sided with the Court’s liberals more than any other conservative justice and authored such liberal opinions as Lawrence v. Texas, which overturned state sodomy laws, was not only solidly in the conservatives’ camp in overturning Obamacare; he was, in fact, reports indicate, its leading opponent and the justice who lobbied hardest to keep Roberts in the fold.

You can read the full text of the Court’s healthcare decision here.