The legal argument from the Obama administration in support of the Affordable Care Act has always been straightforward: the Commerce Clause empowers the federal government to regulate interstate commerce; the American health care system is interstate commerce; and the Affordable Care Act regulates the health care system. Ergo, the ACA fits comfortably within the confines of the Commerce Clause.

The right, narrowing in on the individual mandate, says this is all wrong. The government has the power to regulate interstate commercial activity, including health insurance, conservatives argue, but those who choose not to buy coverage aren’t engaging in an activity; they’re engaging in inactivity. Therefore they fall outside the law’s reach, and the mandate is unconstitutional.

This has always been a very poor argument. When the 6th Circuit announced today that the health care is perfectly constitutional, the three-judge panel had no use for the right’s activity/inactivity argument. Adam Serwer explained:

Martin rejected the notion that going without health insurance constitutes an “inactivity” that can’t be regulated under the Commerce Clause, noting that, “The uninsured cannot avoid the need for health care, and they consume over $100 billion in health care services annually.” Martin adds that “Self-insuring for the cost of health care directly affects the interstate market for health care delivery and health insurance. These effects are not at all attenuated as were the links between the regulated activities and interstate commerce in Lopez and Morrison.”

That last point is key, because Republican appointees, conscious of the fact that Justice Antonin Scalia’s opinion in Raich stands as a substantial obstacle to arguments against the idea that the individual mandate is unconstitutional, concocted the “inactivity/activity” distinction as a rhetorical loophole that would allow Scalia to avoid the implications of his argument that “where Congress has the authority to enact a regulation of interstate commerce, it possesses every power needed to make that regulation effective.”

Keep in mind, all three judges on the 6th Circuit panel agreed on this point. Two of the three were put on the bench by Republican presidents, and one is very conservative.

In other words, this was a no-brainer.

As it should be. Yes, there may be folks who don’t want to buy insurance, and they would be penalized under the law. But under our system, those folks still get sick, still go to the hospital with medical emergencies, and — here’s the kicker — still get care. As you may have noticed, for quite a while, it’s been one of the right’s favorite arguments: the uninsured can always just go the emergency room and receive treatment, whether they have insurance or not.

Of course, when the uninsured get this care, and can’t pay for it, the costs are passed on to the rest of us — it makes the entire system more expensive, with hospitals and medical professionals providing care without compensation from the patient. As a consequence, those who would choose not to get coverage have a significant impact on the larger health care system, which is precisely why the notion of a mandate enjoyed broad, bipartisan support up until late 2009. There was never any doubt as to its constitutionality.

Obviously, the matter will eventually be resolved by the U.S. Supreme Court, but conservatives expected to do well at the 6th Circuit. Today’s ruling should undermine the right’s confidence a great deal.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.