There was a fair bit of discussion at the severability argument about injecting a dose of realism into the Court’s severability doctrine, taking into account the difficulty of overcoming Congressional inertia.
Any decision finding that any part of a statute is unconstitutional means that the law will not operate as Congress intended. And no matter what decision the Court makes on severability, Congress has the power to correct, either by repealing provisions the Court leaves standing or re-enacting provisions that the Court refuses to sever from the unconstitutional provision. So, in a sense, what we are really talking about is the establishment of a default rule, that is, what happens in the absence of action by Congress to fix the statute after a judicial decision finding part of the statute unconstitiutional.
But that default rule matters a lot because of Congressional inertia. So if the Court wants to move in the direction of realistically considering Congressional inertia, perhaps it should be considering what decision on severability is most likely to elicit a response that could overcome Congressional inertia. Viewed from that perspective, wouldn’t the position of the amicus – severing the individual mandate from the rest of the statute so that everything survives except the mandate – fit the bill? Insurers would presumably kick and squawk, but aren’t they precisely the ones in the best position to overcome Congressional inertia?