From what I understand Chief Justice Roberts, who has issued the overall opinion, found the individual mandate constitutional, not under the Commerce Clause, but under the Congress’ authority to tax. So the penalty for not buying health insurance is essentially equivalent to a tax. There are a few complications with that in that currently there is no penalty for not paying the penalty, but Treasury may be able to fix that through regulations depending on the way it’s written.
The Court also threw a monkey wrench into the expansion of Medicaid by essentially removing the penalty against states for not going along with it. However the carrot approach could work better there than the stick.
A lot of analysis to be done but overall a pretty good day for the Prez.
UPDATE: I saw some speculation the last couple of days that Justice Alito’s sad temper tantrum directed at Obama over the Arizona immigration act ruling was a sign that he was not happy with the way the ACA decision was coming down. Didn’t want to say anything about it cuz I’m superstitious that way, but looks like it was spot on! And Scalia seriously needs to consider retiring before he embarrasses himself any more than he has.