LIKE champagne, tequila may be called tequila only if it comes from a specific region. Distillers in five of Mexico's 31 states have the exclusive right to produce the famous firewater. Bottlers elsewhere must use alternative names, though their product is distilled in the same way from the sap of the agave, a spiky desert succulent often wrongly referred to as a cactus.

Demand for tequila is growing fast. Americans now drink more of the stuff than Mexicans—a head-throbbing 120m litres a year. Producers outside the official tequila region are cashing in. The “agave liquor” they sell is cheaper than real tequila and tastes identical, at least to the barbarian gringo palate.

Traditional tequileros hate to see others crashing what they see as their party. So a proposal sponsored by the National Chamber of the Tequila Industry would ban distillers outside the five-state boundary from using the word “agave” to describe their drinks. The proposal has won the support of Mexico's intellectual-property agency, IMPI.

Agave-lovers think this a bit unreasonable. “Agave” is the name of a plant, not a product. It is as if the Champagne region were to try to ban others from using the word “grape” or the butchers of Parma were to claim the word “ham”. A letter from 343 experts, from biologists to sociologists, expressed “forthright opposition” to the proposal.

Others, however, sought similar favours. On January 5th 150 makers of mezcal (another agave spirit) from the state of Michoacán marched on the offices of IMPI to demand that the protected zone include their farms.

The tequileros' proposal may fail. Mexico's competition authority has issued a non-binding opinion against it, and the government's regulatory commission seems unconvinced. If they can't use the law to crush competitors, tequileros will have to make money the old-fashioned way, by making better tequila.