Assume, for the moment, that the Supreme Court rules that the mandate does not exceed Congress’ powers under the commerce and necessary and proper clauses. (This assumption was probably a safe one for most progressives until Tuesday morning.) The ruling sparks howls of outrage and Republicans win comfortable majorities in Congress this November and Mitt Romney takes the White House.

Congress subsequently determines that Americans can no longer feel sufficiently secure in their homes. Law enforcement, while adequate in some parts of the country, is seriously deficient in others; the rich can hire private security to protect their life, liberty, and property, but no such luck for everyone else. This lack of human security is adversely affecting the national economy; people are losing wages due to injury and death that might be prevented by deterring violent crime. Accordingly, Congress decides, pursuant to its power under the commerce and necessary and proper clauses, to pass a law requiring all Americans over the age of 18 to purchase a firearm. Not just any firearm—because Congress has decided there might be a need to shoot at an intruder from a distance and avoid disturbing the neighbors, the firearm must be equipped with a scope and a suppressor (“silencer”), even though most Americans will never need to shoot anyone at a distance or without waking up the neighbors. And, to ensure that there will not be any shortage of bullets, all firearms complying with the mandate must fire a standard cartridge, so many existing firearms will have to either be retrofitted or replaced to comply. The poor will receive a subsidy sufficient to purchase a firearm meeting these standards. Individuals not presenting proof of ownership of a firearm annually, as part of their tax return, will receive a non-tax penalty for non-compliance, which will be garnished from IRS refunds but otherwise not collected. This law is passed by both chambers of Congress and signed into law by President Romney.

Your challenge, should you choose to accept it: find some way to distinguish the Obamacare case, Florida v. Health and Human Services, from this hypothetical.

As everyone knows, it’s Obamacare Week at the Supreme Court (perhaps the less interesting version of Teen Week on Jeopardy!), and today was the main-event showdown over the constitutionality of the mandate. All observers agree it wasn’t the Solicitor General’s finest hour, but Supreme Court cases aren’t really decided by the quality of the oral argument in most cases, and the SG is playing with house money anyway—across the history of the Supreme Court, the solicitor general usually wins (around 70–75% of the time).

Leaving aside the tea leaves, and the wishful thinking that typified people on both sides of the debate going in, the question that strikes me is why the law’s defenders have become so hung up on the mandate question itself. Barack Obama himself campaigned against it in the primaries back in 2008, and even today most people acknowledge that the only real harm from a lack of a mandate would accrue to the insurance companies who’d be stuck taking all comers without getting a mandatory buy-in from the young and healthy, who last I checked were hardly at the top of most liberals’ Christmas card lists. Even there the harm can’t be that great; Obamacare expands Medicaid eligibility substantially, and most of the young and healthy will be staying on parents’ insurance policies well into their twenties (except for, ironically enough, the military’s TRICARE plan). Abolishing the individual mandate wouldn’t get rid of the employer mandate (indeed, neither side is contesting the constitutionality of that). If adverse selection does drive insurers out of business—a big if—doesn’t that just put us one step closer to the single-payer system that liberals (and even some libertarian-leaning conservatives like James Joyner) support?