There are a lot of things that Americans fear about the Patient Protection and Affordable Care Act.  They fear that they won't be able to continue to go to the doctor whom they trust.  They fear that once a single consumer -- the government -- replaces 300 million consumers of drugs and medical technology and then begins to regulate costs, the spigot of medical miracles will slowly shut off (just such regulation and results are already a reality in Europe).  Americans fear the disappearance of choice of treatment as they age and the inevitable appearance of death panels (a prelude to which -- mandatory end-of-life counseling for Medicare beneficiaries -- is already materializing in Massachusetts).  But perhaps Americans' greatest fear of all is that Obamacare is a one-way door -- that it has been plainly designed, rammed through, and implemented with an aim to being irreversible.

President Obama and the liberal cognoscenti clearly think about universal health care in transcendent terms.  In the run-up to the passing of PPACA, Obama frequently invoked the repeated efforts in American history to establish some form of socialized medicine.  The fact that Americans had, time and time again, rejected such a system was only evidence that the system's advocates hadn't tried hard enough.  The same kind of thinking applies, by the way, to "comprehensive immigration reform."  We haven't done it -- yet.  Indeed, the idea that history is like a great ratcheted wheel that the enlightened must painstakingly turn, notch by notch, in order to haul the ignorant masses up out of brutality and chaos is inherent in the liberal project.

The origin of this basic liberal conceit is something which conservatives do well to grasp and take seriously -- namely, the observation that societal ethics do appear to recognize time's arrow.  Aided, no doubt, by ever-increasing prosperity, humanity has clawed its way out of unspeakable barbarity.  And with that evolution, certain kinds of irreversible changes, such as those brought about by the civil rights movement, have ultimately attracted essentially unanimous approval.  So the profound ruthlessness with which Pelosi, Reid, and Obama passed PPACA was a direct outgrowth of the moral certitude that they learned in the struggle for human rights.  For progressives, psychologically, every struggle brings them back to Selma, Alabama.

But 20^th-century history is replete with examples of irreversible (or at least very difficult to reverse) changes -- in the form, for example, of people's revolutions -- that tended more toward slavery than away from it.  Nothing says one-way door better than "one man, one vote, one time."  Just because a historical change is irreversible doesn't make it good.  In contrast to good irreversible changes, such as the recognition of the equality among men of individual rights, bad irreversible changes typically involve the amassing of power by individuals or factions, often (always?) with the ostensible intent of common benefit.

So it is the case that people in general, and Americans in particular, are deeply suspicious of changes which can't be undone.  The American ethos of vaulting fearlessly into each new epoch contrasts paradoxically (or perhaps not so) with the peculiarly American heartache of finding yourself somewhere from which you can never get back home.  At a personal level, the contemplation of many if not all of life's irreversible changes (death, dementia, matrimony...) inspires well-deserved trepidation.  And so the genius of the American Constitution can be viewed as its construction of a system which embodies certain agreed-upon irreversible changes in its amendments while protecting against the tyrannical forms of irreversible change that result from the triumph of faction.

...which brings us back to Obamacare, which now faces the test of which kind of irreversible change it really is, to be decided by the U.S. Supreme Court.

There was unmistakable panic in Nancy Pelosi's voice when, following the passage of PPACA, she was first confronted with a question as to the constitutionality of the individual mandate at a press conference and she responded: "Are you serious?  Are you serious?"  From the perspective of someone who has just mightily heaved history forward a notch (after a century of effort), panic was the natural response.  It was a quintessential horror-movie-false-ending situation -- the profound relief she was feeling was, alas, premature.

When Florida Federal Judge Roger Vinson ruled in January that, in accordance with the arguments of plaintiffs (including representatives of 26 states), the individual mandate requiring all citizens to buy health insurance exceeded the authority of the Commerce Clause of the Constitution, and, furthermore, since the makers of the law had designed PPACA without a severability clause, the whole law was therefore null and void, the response in the liberal community was, again, panic.  More than any other ruling to date, Vinson's decision has cleared a legal path to the termination of Obamacare.  And the supporters of the law know it.

Harvard Law School Professor Lawrence Tribe was at the forefront, but by no means alone, in the bluster with which he denounced Vinson's ruling in a famed New York Times op-ed.  Tribe employed economics, he employed misdirection, and he employed more than a touch of bullying in trying to chart a course back to safety for PPACA.  But the message of Tribe's piece was panic.  Tribe used more words than Nancy Pelosi, but in the end, what he said was: "Are you serious?  Are you serious?"

The legal argument in favor of admitting Obamacare under the auspices of the Commerce Clause comes down to a simple assertion.  As succinctly stated by Tribe:

[Attempts to invalidate the law depend] on the theory that Congress is entitled to regulate only economic "activity," not "inactivity," like the decision not to purchase insurance. This distinction is illusory. Individuals who don't purchase insurance they can afford have made a choice to take a free ride on the health care system. They know that if they need emergency-room care that they can't pay for, the public will pick up the tab. This conscious choice carries serious economic consequences for the national health care market, which makes it a proper subject for federal regulation.

In addition to being simply incorrect, this argument is ahistorical as well as insulting.

Until quite recently in American history, most people, when they became ill, went to a doctor, and, upon receiving a bill for the doctor's services, they paid it.  Nowadays, most people who choose not to buy health insurance do so not because they are poor, but because they are young.  They are betting (and usually the odds are in their favor) that they will stay relatively healthy.  But still, in most cases, when such people get sick, they pay their doctor.  To say that their intention upon not buying health insurance is to bilk the rest of us is to fail to realize that most people in America take their financial obligations seriously.

The most pertinent fault of Tribe's argument, however, is to establish a chain whereby the regulated activity, in some cases, is causally linked with an undesirable economic consequence.  It is not failing to buy insurance that causes economic damage -- it is failing to pay the doctor's bill.  Thus, an ultimately statistical argument is being used as a moral arbiter of behavior.  By this reasoning, the Commerce Clause would permit, for instance, establishment of a legal requirement that mothers be married to the father of their children before being allowed to give birth, since it is well-established that children of single parents are far more likely to incur upon society the cost of incarceration (as well as many other consequences of crime).

The recent revelation that Tribe shared in the triumph of Obamacare's passing with now-Supreme Court Justice Sotomayor is of course not surprising.  As one who has seen the wheel of history moved forward a notch, he and fellow liberals have tried to browbeat the Supreme Court into not allowing it to slip back.  But the Supreme Court's duty is not to be concerned with the direction of history.  Rather, its job is to determine whether the laws placed before it are constitutional.  As Robert Bork once said:

Those who made and endorsed our Constitution knew man's nature, and it is to their ideas, rather than to the temptations of utopia, that we must ask that our judges adhere.

After all, the irreversible road to utopia often turns into the irreversible road to serfdom.

The author is a nanophysicist at Harvard University.  He ran for Congress in MA-03 in 2010.