You must insure your vehicle (of life)

In  arguments about the Constitutionality of the individual mandate in the Affordable Care Act, proponents have pointed out that the law obligates car owners to buy auto insurance, because the costs incurred and inflicted by uninsured drivers would be absorbed by the state.  Opponents have countered that no one is forced to own a car, and hence the state does not force us to buy car insurance. The ACA, by contrast, mandates that everyone buy health insurance, regardless of any prior economic decision.

There is a "vehicle" that each of us owns, however: our bodies. And while we don't "choose" to own them, we do choose to maintain them.  If we don't insure, we self-insure -- that is, make what provision we can to pay for the health care that we will inevitably consume.  But the self-insured rely on a massive reinsurer or stop-loss insurer whom they don't pay: the state. Federal and state law decree that no one may be denied care.  Hence failure to carry health insurance is an economic decision that affects the larger community. "Self-insuring" constitutes economic activity that may be regulated by Congress.

That is the thrust of the 2-1 majority decision in the U.S. Court of Appeals, 6th Circuit, upholding the individual mandate in Thomas More Law Center v. Obama.  Timothy Jost explains that Judge Boyce Martin, writing the majority opinion, redefined the question of whether the mandate regulates "inactivity" as opposed to economic activity:

Judge Martin contends that nearly every individual in the United States consumes health care, and thus must decide whether to purchase insurance or to self-insure.  Self-insuring is no less an economic activity than purchasing insurance.  Self-insuring results, however, in a substantial cost-shift when those who choose to self-insure cannot in fact cover the cost of their care.  For 2008, $43 billion dollars worth of care was passed on by those who chose to self-insure to others.  Thus self-insuring has a substantial impact on interstate commerce.

In fact Judge Martin also asserted that there is nothing in the Constitution or case law to prevent Congress from regulating 'inactivity" if the so-called "inactivity" affects interstate commerce:  "the text of the Commerce Clause does not acknowledge a constitutional distinction between activity and inactivity, and neither does the Supreme Court" (p. 23).    

That said, Martin also argued positively that the individual mandate "regulates active participation in the health care market" (p. 26, my emphasis).  Here again, the concept that those who do not buy health insurance effective self-insure is key: no one, insured or not, is inactive in the health care market; insurance determines who pays; and those who self-insure in aggregate pass their costs on to the insured.  Those who self-insure do so "cognizant of the backstop of free services required by law" (p. 19).

At one point, Judge Martin waxed a bit paradoxical:

The activity of foregoing health insurance and attempting to cover the cost of health care needs by self-insuring is no less economic than the activity of purchasing an insurance plan ...

Virtually everyone requires health care services at some point, and unlike nearly all other industries, the health care market is governed by federal and state laws requiring institutions to provide services regardless of a patient's ability to pay. The uninsured cannot avoid the need for health care, and they consume over $100 billion in health care services annually...This cost-shifting inflates the premiums that families must pay for their health insurance "by on average over $1,000 a year" (pp. 19-20, my emphasis).

I could imagine that phrase "the activity of foregoing health insurance" becoming a battleground. It might be argued "foregoing" is not an activity, and that not every individual who forgoes health insurance for a time will end up"affecting interstate commerce" by accessing care paid for by someone else. There, though, Martin's second line of defense comes into play: the distinction between activity and inactivity is moot:

The Supreme Court has never directly addressed whether Congress may use its Commerce Clause power to regulate inactivity, and it has not defined activity or inactivity in this context. However, it has eschewed defining the scope of the Commerce Power by reference to flexible labels, and it consistently stresses that Congress’s authority to legislate under this grant of power is informed by “broad principles of economic practicality.” Lopez, 514 U.S. at 571 (Kennedy, J., concurring)...

Similarly, this Court has also refused to focus on imprecise labels when determining whether a statute falls within Congress’s Commerce Power. For example, we rejected the argument that the Child Support Recovery Act is unconstitutional because it regulates an individual’s failure to place an item in commerce. Instead, we held that Congress had a rational basis for concluding that a non-custodial spouse’s failure to send court-ordered child support payments across state lines substantially affects interstate commerce...

Here, too, the constitutionality of the minimum coverage provision cannot be resolved with a myopic focus on a malleable label. Congress had a rational basis for concluding that the practice of self-insuring for the cost of health care has a substantial effect on interstate commerce, and that the minimum coverage provision is an essential part of a broader economic regulatory scheme. Thus, the provision is constitutional notwithstanding the fact that it could be labeled as regulating inactivity.

The two arguments effectively bleed together: foregoing health insurance is an "activity" because that decision affects the broader healthcare market; and because it affects the market, any sense in which it might be deemed "inactivity" is not material.