Since Tuesday’s oral arguments in Virginia v. Sebelius—the first Obamacare challenge to reach the circuit court level, and one in which Cato also filed an amicus brief—the legal blogosphere has been discussing the Fourth Circuit panel’s incredulity concerning the activity/inactivity distinction at the heart of our arguments against Obamacare. As Ilya Shapiro explains, we contend that if Congress’s power to regulate “interstate commerce” reaches the inactivity of not buying health insurance, then there is nothing it does not reach. The Supreme Court will eventually have to grapple with this question and decide whether the distinction is constitutionally meaningful.

As Volokh conspirator Jonathan Adler points out, the activity/inactivity distinction is long-standing. At common law, there was no legally enforceable duty to rescue. In other words, if you didn’t act to create the danger, you would not be liable for your inactivity in not helping. To put it bluntly: you would have no legal liability if you ignored a drowning child.

Legal philosophers have grappled with the meaning of “act” and “omission” for centuries. While there are some difficult issues to ponder, there is also an element of navel-gazing in the question and the Supreme Court may have to gaze long at their navels to answer it. But it is worth remembering why the act/omission distinction matters in a free society. At the risk of getting too philosophical, I will add some thoughts of my own.

Anyone who has been to law school has likely had long conversations, probably in torts class, over whether the act/omission distinction is both meaningful and moral. If your torts class was like mine, your professor lamented the “no duty to rescue” rule as evidence of our individualistic and selfish society. Many law professors believe our slavish adherence to the act/omission distinction not only allows us to let children drown, but that it is just another “Western” belief that holds back a robust welfare state.

The aversion to mandating action, however, is not about letting children drown. I wouldn’t let a child drown and I imagine you wouldn’t either. The extreme hypothetical helps gloss over a meaningful principle for normal, run-of-the-mill cases. Just as bad facts make bad law, bad hypotheticals can blur vital principles. The act/omission distinction helps delineate, albeit imperfectly, the personal sphere of control and the governmental sphere of control.

Despite many who want to equate the two, what is legal is not the same as what is moral. In fact, these two categories can work against each other—performing an act of kindness because you fear authority diminishes the act’s moral character.

But we distinguish between the legal and the moral for deeper reasons as well: it helps maintain the crucial separation between the government and civil society, ensuring that the government doesn’t become the absolute ruler of our lives and the values we choose to hold dear. The theory that there are proper spheres of governmental control and proper spheres of private control is one of the great and under-appreciated victories of Western culture.

The act/omission distinction also matters because resources are scarce. Acting uses resources that could be used for alternate purposes. Omitting uses none. While you can take on a literally infinite set of omissions, you can only take on a finite number of acts. Using resources—time, money, strength, natural resources, etc.—for one thing means they are not being used for something else.

To put this in real-world terms: Obamacare’s individual mandate to maintain minimum health care coverage could eventually cost someone tens of thousands of dollars that they would have spent on other things. One of those things may have been another 50” television. However, it is just as likely that the money may have been spent on sending a child to college (or, given the age of those likely to go without insurance, sending oneself to college), donated to a church or a favorite non-profit, or invested in a fledgling business. Mandating action—that is, the use of scarce resources—overrides individual value preferences and substitutes other values through force. In other words, the government is telling you that your value preferences are wrong.

This is how the necessary distinction between government and civil society is slowly eroded. Creating legally enforceable duties to use your resources politicizes resource allocation problems. But our lives are already resource allocation problems, with or without government. How you manage your time and efforts is not just a question for your day-planner, it’s a profound existential quandary. Politics is one of the worst ways that resource allocation problems can be addressed. At the extremes, it becomes dehumanizing. Special interests will fight over your resources and decide how they should be allocated. It’s actually worse than watching sausages get made.

This is why libertarians are treating the Obamacare litigation as a critical moment in constitutional law. Sure we’ve been taxed before, and civil society has already been significantly eroded by government overreach. But we’ve rarely been commanded, particularly in a way so obviously designed to avoid political liability for raising taxes. Our parades of horribles—for example, the hypothetical “buy broccoli mandate”—may elicit eye-rolling from some, but violating the act/omission distinction in principle, as the government threatens to do here, means a principle is no longer standing in the way.  “Just this once” is hardly reassuring.

I understand that much of what I’ve said here, if taken to its logical conclusions, would prohibit any taxation. I am not advocating that. I am only pointing out a subtle and important distinction through which these questions can be viewed. A government that has total power to dictate when, how, and whether resources will be used is a government that has the power to dictate your life-plan and decide for you which things matter the most. The act/omission distinction has helped maintain the crucial line between the private and the public spheres, allowing for the possibility that government can be avoided by keeping to oneself.

The fact that the Fourth Circuit judges were “baffled” by the action/inaction distinction is disturbing to say the least. We lose something very important if they rule for the government, something that generations of enlightenment-era political philosophers articulated as a critical line between freedom and total government control. Let’s hope the Supreme Court doesn’t also forget those lessons.