IN THE wild, horses eat tough grass that naturally wears down their teeth. In captivity, they are fed softer food they can eat more quickly, so their teeth grow unchecked. Unless filed down—a process known as “floating”—they can grow too long and cut the horse's cheeks. Floating is hard work. Carl Mitz has been doing it for 22 years. He calms each horse before holding its mouth open and vigorously filing its teeth by hand until they are just so. A third-generation horseman, he says he has handled 100,000 horses. His customers are satisfied, judging by the sheaf of testimonials on his desk. But the Texas State Board of Veterinary Medical Examiners wants to shut him down.

Mr Mitz may be a skilled artisan, but he is not a vet. And the board says that only vets may float horses' teeth. If Mr Mitz persists in doing his job, he will be practising veterinary medicine without a licence. The penalty could include steep fines and even prison. Mr Mitz is miffed. Even if he could get into vets' school, which he doubts, he could not possibly afford the fees. And he does not see why he should take years off work and pay tens of thousands of dollars to pursue studies that may not help him in his work. Vets' schools typically teach little about equine dentistry. “It's ludicrous,” he says.

Mr Mitz is one of four horse-tooth floaters in Texas suing to be allowed to carry on earning a living. The case attracts few headlines, but the principle is important. Regulators should not shut down an honest business without good cause. The vets' board says letting non-vets file horses' teeth endangers the horses. Dewey Helmcamp, the executive director, says the board received half a dozen complaints in a year and a half about poor care from fly-by-night floaters. But that label hardly applies to Mr Mitz, who says he has never botched a floating. His customers fear that they may have to pay a vet more to do the job less well. “This should be my choice, not yours!!!” reads a typical letter from one of Mr Mitz's clients to the board.

Supporting Mr Mitz's lawsuit is a group called the Institute for Justice, which fights affronts to economic freedom, such as licensing rules designed to protect incumbents from competition. These typically purport to protect consumers, but often serve mainly to jack up prices by deterring newcomers from setting up shop. In Minnesota, for example, the state board of barbers and cosmetologists barred African hair-braiders from braiding hair unless they underwent 1,500 hours of irrelevant training, until the institute took up their case and won.

For competition-shy incumbents, no risk is so trivial that government action is not required to avert it. In four states, you need a licence to practise interior design. In several more, you can do the job but you can't advertise yourself as an “interior designer” unless you pass a state-mandated test (of fabulous taste, presumably). The only people lobbying for such regulations are established interior designers. The net result is less competition and higher prices. But with no one organised to lobby against them, the rules often pass.

Overall, the benefits of regulation in America far outweigh its costs, says the White House's Office of Management and Budget. Between 1996 and 2006, it puts the annual cost of the main federal regulations at between $40 billion and $46 billion, whereas these rules yield between $99 billion and $484 billion in annual benefits. Yet many experts doubt these figures. Jerry Ellig of George Mason University notes that they are based on the estimates various agencies make when they propose rules, with little attempt to measure how they work in practice. The Competitive Enterprise Institute, a conservative think-tank, reckons that the true cost of all federal regulations is a whopping $1.1 trillion a year, a figure that includes the burden of price supports, barriers to entry and complying with the tax code. For a small firm, complying with federal regulations costs $7,600 per employee per year, according to a report prepared for the Small Business Administration.

Hard to quantify, especially if you don't try

Experts admit that they don't even know whether the regulatory burden is growing or shrinking. Since the 1970s, many rules have been revoked. Price controls are a distant memory and several industries, from airlines to banking, have been deregulated. But rules relating to health, safety, the environment and national security have multiplied. Some of these are necessary, but many are not. For example, by one estimate, American health-care regulations cost $169 billion a year more than they yield in benefits, and lead to 7m Americans not being able to afford health insurance. By another estimate, measures to keep terrorists off aeroplanes cost lives by prompting people to drive instead of fly, which is nine times more dangerous.

Many of the effects of regulation are hard to measure. But a deeper problem is that politicians often don't try very hard to weigh costs against benefits at all. After an exhaustive study of American regulations, Robert Hahn of the American Enterprise Institute, a think-tank, concluded that quite a lot of cost-benefit analysis is done, but it is sometimes shoddy and politicians often ignore it.

Politicians are reluctant to be seen opposing almost any rule aimed at thwarting terrorists, or to allow economists to put a price on a human life (hence all the health-care rules) or a pristine landscape. And even the worst regulation usually heaps benefits on a small group, while its costs are widely spread. The beneficiaries thus lobby hard to keep each rule, while its victims do nothing. The late Mancur Olson, an economist, predicted that interest groups will grow in number until they cause their host society to slip into economic decline. America is nowhere close to that. But it surely needs more watchdogs (and horse floaters) to growl at the regulators.