This morning, shortly after 10 am, Chief Justice John Roberts will open oral argument in U.S. Department of Health and Human Services v. Florida on the issue of whether challenges to ObamaCare’s individual mandate are barred at this time by the Anti-Injunction Act (AIA).  The AIA requires individuals challenging most taxes to first pay the tax, seek a refund, and then sue the federal government for denying such a refund—putting off challenges to the mandate until 2015 at the earliest. The Supreme Court will hear arguments as to whether the mandate penalty is a tax.

This is definitely not one of the blockbuster legal issues presented by the ObamaCare challenges, but today’s oral argument could be terribly revealing in more than a few ways.  The federal government now argues the AIA does not bar the suit because the mandate penalty is not a tax for statutory purposes.  The 26 state challengers and the NFIB have four other arguments why the AIA dos not apply, so the Court appointed a third lawyer to argue that the AIA does bar the suit.

Here’s what veteran Court-watchers will be looking for:

First, do Justice Scalia and Chief Justice Roberts tip their hands on the AIA issue? Scalia is widely viewed as the most demanding when it comes to the federal courts’ power to decide particular cases, believing that the courts should not thrust themselves into controversial matters where not authorized to do so.  And the Chief is widely viewed—not altogether correctly—as a “minimalist” who favors narrow decisions that, when reasonably possible, duck controversial issues.  If Scalia or the Chief signal their belief that the AIA bars the mandate challenge at this time, that could carry weight with their colleagues on the Court. I’ll be watching the Chief, who often acts as a traffic cop at oral argument, to see how he steers the discussion.

Second, what do the justices’ questions hint about whether the states are covered by the AIA?  The district court and the Eleventh Circuit that considered the 26-state lawsuit never considered the states’ legal standing to challenge the mandate because it was enough that individual plaintiffs had standing to support the challenge.  But questions by the justices about the states’ standing could point to an easy way through the AIA thicket because the states (if they have standing) should not be subject to the AIA for two reasons.  A decision on this ground, however, also could make it easier in the future for the states to sue to enforce limits on federal power, much like last Term’s decision in Bond v. United States.

Third, what about the merits? Lawyers typically distinguish between preliminary issues in a case, like the AIA, and the heart of the lawsuit, or merits.  But the barrier between the two can break down, and justice are often eager to get beyond the preliminaries to the interesting bits.  We “[s]ometimes have to peek at the merits to see if there’s standing,” an impatient Justice Kennedy said to counsel at oral argument last Term.  It would come as little surprise if the justices—and Justice Kennedy in particular—want to “peek” a bit at the issues to be considered in coming days, particularly regarding the constitutionality of the individual mandate.  If so, how many justices will bring up the President’s infamous statement to George Stephanopolous that the mandate is not, in fact, a tax?

Fourth, does the Court care about the consequences if it declines to rule on the mandate at this time? Deciding that the AIA bars the most important issue in this litigation may mean that ObamaCare goes into full effect before the Court has an opportunity to address its lawfulness in 2015 or beyond.  ObamaCare alone is expensive enough; an additional four or more years of uncertainty as to whether the Court will strike it down will cause even more pain.  To what end?  Many of the justices are, to varying extents, pragmatists, and they will want to know what happens between now and 2015.  If they buy the argument of exploding costs and other problems, that may influence what they think about the AIA and ObamaCare as a whole.

Today’s argument probably won’t tell us how a majority of the Court regards the merits, but it will do more than just set the tone for the days ahead.