Nothing is certain merely from listening to oral argument at the Court. But it sure seemed as if a large majority of the justices (and perhaps all of them) thought the Court has jurisdiction in this case and can proceed to address the merits of whether the minimum essential coverage provision is within Congress's enumerated powers. There were several different theories, and there seemed to be some sharp disagreement as to whether the AIA is jurisdictional in nature. But it also seemed that a majority of justices could agree on a narrower proposition, something along these lines: (1) statutes stripping the courts of jurisdiction are generally construed narrowly, meaning that Congress must make its intent clear; (2) the ACA--especially in specifically demarcating the exaction in 5000A(b) a "penalty"--did not make Congress's intent for the AIA to apply clear; thus (3) even if the AIA is jurisdictional, it does not apply to the penalty imposed in 5000A(b). (Perhaps some justices might concur only in the judgment, finding that the Government can waive the AIA in certain circumstances, as it did in Davis.)
No doubt, the meaning of the AIA (and whether it is jurisdictional in nature) are somewhat important in their own rights. But in the broader scheme, what matters from today is that the Court is almost certain to get to the minimum coverage provision's constitutional merits. That is the question for tomorrow--the biggest single day at the Court since December 2000.