One of the most appalling recent trends is the way in which certain media outlets, such as The New York Times, have begun referring to carbon dioxide — one of the basic constituents of the atmosphere and a substance we all constantly exhale — as a "pollutant."

By that standard, everything is a pollutant. And that is, in fact, precisely the view that has now been endorsed by a 5-4 majority of the Supreme Court. In Monday's ruling in Massachusetts v. Environmental Protection Agency, the court held that the EPA is obliged to treat every substance on earth as a pollutant to be regulated, unless it can demonstrate why that substance is not a pollutant.

Actually, that's not precisely true. The EPA is not required to target literally every chemical component of our environment — just the ones that are produced by humans as part of our economic activity. The court's majority opinion cites the Clean Air Act, which defines an "air pollutant" to be "any physical, chemical...substance...emitted into...the ambient air." Emitted, that is, by humans. The emphasis on the word "any" was added by the court, which goes on to note that this "embraces all airborne compounds of whatever stripe."

In a puckish footnote in his dissent, Justice Antonin Scalia replies: "It follows that everything airborne, from Frisbees to flatulence, qualifies as an 'air pollutant.' This reading of the statute defies common sense."

But following the implications of this "everything is pollution" premise, the court concludes that the "EPA can avoid promulgating regulations only if it determines that greenhouse gases do not contribute to climate change." If emitting carbon dioxide is not explicitly permitted by the EPA — then it is assumed to be forbidden. As my friend Jack Wakeland put it to me, the upshot of this Supreme Court ruling is that "industrial civilization is guilty until proven innocent."

This ominous decision overturns the basic rule of a free society. In a free society, that which is not explicitly forbidden is permitted. As philosopher Harry Binswanger once put it, in a free society we live in a sea of liberty, a vast realm of actions that cannot be impeded by government — with only a few small islands marked "off limits," a strictly delimited set of evil actions like armed robbery and check-forging that are banned by government.

In a dictatorship, by contrast, men are mired in a giant, endless quagmire of government controls, and they have to struggle to establish a few small islands of liberty.

Yet that is the meaning of this ruling: unless your economic activity falls within a little island of liberty carved out by a sympathetic EPA administrator, it is automatically assumed that it must be regulated. That which is not explicitly permitted is forbidden.

The particular mechanism by which this environmental tyranny is to be enforced is laid out in the majority's re-write of the rules regarding who has "standing" to sue. The rules on "standing" are one of our basic protections from legal harassment. These rules say that someone can't sue you simply because he has a general, free-floating grievance against society. Instead, to have standing to sue, the plaintiff must make a reasonable case that he has been directly harmed, or is in imminent danger of being harmed, by your specific action.

Chief Justice John Roberts's dissent in this case is a masterful overview of the rules on standing — and a devastating analysis of how these rules are all thrown out by the majority decision.

The case was brought by the state of Massachusetts, as lead plaintiff, on the grounds that the EPA's failure to raise automobile mileage standards would allow more carbon dioxide to enter the atmosphere, contributing to global warming, which would then, allegedly, cause rising sea levels to inundate the Massachusetts coastline — 100 years from now.

That last part is important. Roberts notes that traditionally a plaintiff is only allowed to file a suit if he can claim some imminent harm. A harm projected to occur a century from now, long after we are all dead, is by definition not imminent.

Moreover, even granting that human emissions of carbon dioxide cause global warming (which is a far more dubious proposition than we have been led to believe), an increase in gas-mileage requirements would have only a marginal effect on US automobile emissions of carbon dioxide, which are only a marginal fraction of total worldwide human emissions of carbon dioxide — which, in turn, is only a fraction of the carbon dioxide and other greenhouse gases produced by natural, non-human sources.

Finally, there is no clear evidence that global warming is raising or will raise sea levels in Massachusetts. Roberts notes that the computer model used to project future changes in sea levels has a margin of error that is greater than the effect that it claims. The projected rise in sea levels is, in effect, lost in the model's static. As for the plaintiff's claim that sea levels are already rising, he responds:

One declaration states that "a rise in sea level due to climate change is occurring on the coast of Massachusetts, in the metropolitan Boston area," but there is no elaboration. And the declarant goes on to identify a "significan[t]" non-global-warming cause of Boston's rising sea level: land subsidence [i.e., the sea is not rising; the land is sinking]. Thus, aside from a single conclusory statement, there is nothing in petitioners' 43 standing declarations and accompanying exhibits to support an inference of actual loss of Massachusetts coastal land from 20th century global sea level increases. It is pure conjecture.

Thus, Massachusetts is not suing on the basis of direct provable harm, but on the basis of a vaguely indirect, purely speculative harm.

But Roberts grasps what is accomplished by throwing out the rules of standing. Under the open-ended, infinitely elastic rules established by the majority, he notes, establishing a standing to sue become a "lawyer's game" in which any sharp operator can set up a Rube Goldberg chain of cause and effect to show that he is being "harmed" by the activities of others. This allows sweeping new government controls to be imposed, not as the application of predictable existing law, nor as the product of public debate in the legislature, but by the arbitrary decree of a small clique of activist lawyers and leftist judges.

Consider the implications of the court's ruling that the EPA can be sued in the courts to require it to regulate carbon dioxide as a "pollutant." Carbon dioxide is not an incidental byproduct of the generation of power. It is the unavoidable product of our most widely used fuels, fuels for which there is no practical alternative: oil, coal, natural gas. So to cap or reduce carbon dioxide emissions would require a vast regime of government controls on all levels, from giant factories down to backyard barbecues. To cap or reduce carbon dioxide emissions is to cap or reduce American prosperity.

This is one of the most sweeping and intrusive demands for government controls that I can recall. But the court is establishing a mechanism by which all of this can be imposed without legislation—sidestepping the need to convince the American people and secure their consent.

Seeing the popularity of Al Gore's traveling tent revival act, many of us have been preparing for a long and bruising public debate on global warming and a political battle royal over whether to impose a cap on carbon dioxide emissions. We weren't happy that we would have to fight this battle, but we could at least hope that an extended public debate would give us a chance to cool the global warming hysteria and point out the disastrous consequences of a "carbon tax" or the fuel-rationing scheme of "cap and trade."

But the Supreme Court is now telling us that the whole game is over before it even begins: the Clean Air Act, passed some 30-odd years ago, already demands total government regulation of the lifeblood of the economy. Their decree cuts off the debate.

I am not among those who believe that the courts must be entirely deferential to the legislature and the executive. The Supreme Court in particular has a legitimate realm of authority as the protector of the Constitution. But the court's proper role is as the guarantor of liberty. Its legitimate authority lies in its responsibility to protect the substantive and procedural limits that guard us against tyranny.

What happens when the court abandons that role and takes it upon itself to weaken our protections against government power? We can now get a preview of the result. In the new environmentalist utopia, all that which is not permitted is forbidden, and we are all guilty until proven innocent.