Via TPM, which is aghast at the possibility that the ObamaCare bomb that’s set to drop later this week or next might be even more powerful than Court-watchers have anticipated. Right now people are expecting the judicial equivalent of a grenade aimed squarely at the mandate, but depending upon how the Court sees the severability issue, there’s a chance that we’ll see a cruise missile that takes out the entire statute.

But what about something bigger? What about a Commerce Clause atomic bomb?

Justice Scalia writes, for instance, that he has little use for a central precedent the Obama administration has cited to justify the health care law under the Constitution’s commerce clause, Wickard v. Filburn.

In that 1942 decision, Justice Scalia writes, the Supreme Court “expanded the Commerce Clause beyond all reason” by ruling that “a farmer’s cultivation of wheat for his own consumption affected interstate commerce and thus could be regulated under the Commerce Clause.”…

Justice Scalia’s treatment of the Wickard case had been far more respectful in his judicial writings. In the book’s preface, he explains (referring to himself in the third person) that he “knows that there are some, and fears that there may be many, opinions that he has joined or written over the past 30 years that contradict what is written here.” Some inconsistencies can be explained by respect for precedent, he writes, others “because wisdom has come late.”

TPM notes, quite correctly, that Scalia relied in part on the Wickard decision for his concurrence in the awful, awful Raich case that allowed the feds to regulate marijuana grown for one’s personal use under the auspices of “interstate” commerce. That was seven years ago; evidently he’s had quite the change of heart about the Commerce Clause since then. I wonder why.

Anyway, about that atomic bomb. It’s not breaking news that Scalia is leaning hard against ObamaCare’s mandate: He was the most vocal opponent of the statute during oral arguments, at one point lecturing Obama’s hapless Solicitor General Donald Verrilli about enumerated powers. His vote to strike it down seems a foregone conclusion. What’s more tantalizing, per the passage in his book about Wickard, is the possibility that he might call for the Court to more broadly revisit its Commerce Clause jurisprudence starting with the Roosevelt-era cases that established the precedent that Congress’s commerce power is more or less limitless. Which brings us to the atomic bomb scenario: How many justices would join him on that? It’s no stretch to think Thomas might. What about Alito and Roberts? If five justices signed onto the idea of overturning Wickard, the scope of federal regulatory power would contract dramatically. It would be a true judicial earthquake, with aftershocks far beyond health care.

The odds of that happening are upwards of 1,000 to one, I’d guess, simply because Anthony Kennedy seemed torn about the mandate at oral argument. It’s more likely that we’ll see an opinion affirming broad Commerce powers for Congress but drawing a fine line to explain why the mandate, specifically, went too far. The question isn’t whether there’ll be five votes for a broad rethink on the Commerce Clause this time, then, it’s whether there’ll be two or three or maybe even four votes to move the Overton window and set things up for a broad rethink down the road if/when Romney wins the election and gets to replace him with a bolder justice. In fact, if you do see three or four votes to get rid of Wickard this time, expect the Commerce Clause to soak up vastly more time during Supreme Court confirmation hearings going forward. It’ll rival abortion for the amount of attention it gets, as well it should: The policy implications if the Court reshapes the Commerce Clause are much wider than if it overturns Roe.

For more on how dramatically the Overton window has moved already, read this piece by lefty Kevin Drum. You won’t agree with his conclusion but he’s right that it would have been hard to imagine the Court cracking down on Commerce this hard after the Raich case. Exit question: Is Juan Williams right that public faith in the Court will be shaken if it dumps ObamaCare? Maybe among Democrats. But how about among Republicans and independents?