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Mark your calendars: The Supreme Court decision on the Affordable Care Act's constitutionality is almost certainly going to come down  Thursday about 10 a.m.

The court announced Monday  morning that Thursday would be the last day of this year's term. Unless the justices decide to punt it over until next year — an outcome that is possible, although thought to be unlikely — the decision will come  Thursday.

We don't know how the Supreme Court will decide on the health-care law; the justices tend to be better at keeping secrets than the CIA. But court watchers expect that Chief Justice John Roberts will author the opinion, after seeing Justice Anthony Kennedy write the opinion in the Arizona immigration case. The justices tend to split up the workload each term, especially when it comes to high-profile and complicated rulings.

"From the opinion authorship, health care is almost certainly being written by [Chief Justice] Roberts, perhaps in part with Justice Kennedy," Tom Goldstein writes for SCOTUSBlog.

You might also see some court watchers doing some tea-leaf reading about what the Arizona ruling, partially striking down the state's controversial anti-immigration law, means for Obamacare. For a while now, there's been some thinking that the Supreme Court might split the difference between the two, ruling in the Obama administration's favor in one case but not the other. Brad Joondeph at ACA Litigation blog has written about this idea here.

The court's opinion on Arizona today — which upheld parts of the law, but struck down others — makes it a bit difficult to game out how the two decisions interact. And it leaves us waiting anxiously for Thursday morning.