A DEAD rhino, with a bloody stump in place of its horn, means different things. For the species it is the danger of imminent extinction; for wildlife-lovers it is barbarism; for law-enforcers it is failure. For its poachers it means income; the horn will be exported illegally to fetch tens of thousands of dollars. For economists, it means market forces are at work.

South Africa is in the throes of a poaching epidemic. Official figures show poachers killed 1,054 rhinos in 2016, up from just 13 in 2007. In Kruger National Park, home to the world’s largest rhino population, numbers are dropping despite a fall in recorded poaching incidents. Tom Milliken of TRAFFIC, a wildlife-trade monitoring network, worries that poachers have become better at hiding the carcasses.

The problem is international. The rhino-horn supply-chain sprawls from South Africa, home to nearly three-quarters of the world’s rhinos, to Asia, and in particular to Vietnam, where rhino horn is coveted as medicine, prescribed for fevers, alcohol dependency and even cancer.

Prohibitionists call for better law-enforcement. Demand for rhino horn in China, they point out, fell sharply after the government banned its use in 1993. In the rhino’s homelands, they say, extra patrols, fences and harsher penalties have helped curb poaching in the past couple of years.

But some argue the trade ban might actually be making the problem worse. Restricted supply pushes up prices and pulls in poachers. Private rhino-ranchers argue that if they could sell their stocks of horn, they could undercut the illegal trade. Some already chop off their rhinos’ horns to make them worthless to poachers. Unlike elephant ivory, rhino horn grows back after a few years. Michael Knight, who chairs a specialist group on rhinos at the International Union for Conservation of Nature, an NGO, worries that, if rhino-horn sales remain illegal, ranchers will switch to cattle. They bear the cost of security. Poachers make the money.

But by seeming to normalise rhino-horn use, legalisation might boost demand along with supply. Prohibitionists worry that any attempt to lower prices would both bring in more customers, leaving incentives to poach unchanged, and make it far easier to launder illegal, poached horn.

For them, the best form of conservation is to cut demand. A new study, requested by the Vietnamese and South African governments and overseen by the International Trade Centre, an independent arm of the WTO and the UN, provides information on where that demand comes from. Thanks to contacts in the traditional-medicine business, the academic researchers who conducted the study interviewed rhino-horn users. Disproportionately, these were well-off older men. None used it as an aphrodisiac. And nothing suggested any stigma in using it: if anything, illegality enhanced the product’s exclusivity and hence their willingness to pay. Asked how their demand would respond to price, users confirmed that cheaper horn would increase usage.

But if legalisation is risky, so is maintaining the ban. The study finds a hard-core user base of around 30% of rhino-horn users, who want the stuff regardless of the penalties. So long as doctors prescribe it demand will be difficult to eradicate. Douglas MacMillan, an author of the study, is sceptical that information campaigns persuade many people to shun it. Vietnam has already seen vigorous initiatives pointing out that rhino horn is the chemical equivalent of human hair and toenails.

Changes in the law may yield more evidence. On March 30th South Africa’s constitutional court overturned the ban on domestic trade. Now, if they have the right permit, people can trade rhino horn, but not export it. TRAFFIC’s Mr Milliken worries that this will lead to the worst of all worlds. Allowing some legal trade while the authorities are not properly enforcing the ban on illegal trade will muddy already murky waters. Once out of the country, legal and illegal horn will be all but indistinguishable. So users in Vietnam will have cheaper supplies; the illegal dealers still in control of the export trade will pocket the profits; and rhinos will keep falling to the poachers’ bullets.