Still, legalization would deliver a significant short-term hit to the cartels — if drug trafficking were the only activity they were engaged in. But cartels derive a growing slice of their income from other illegal activities. Some experts on organized crime in Latin America, like Edgardo Buscaglia, say that cartels earn just half their income from drugs.

Indeed, in recent years cartels have used an extensive portfolio of rackets and scams to diversify their income. For example, they used to kidnap rivals, informants and incompetent subordinates to punish, exact revenge or send a message. Now that they have seen that people are willing to pay heavy ransoms, kidnapping has become their second-most-lucrative venture, with the targets ranging from businessmen to migrants.

Another new source of cartel revenue is oil theft, long a problem for the Mexican government. The national oil company, Pemex, loses hundreds of millions of dollars’ worth of petroleum every year to bandits and criminal gangs who tap into pipelines and siphon it off. Now the cartels are getting involved in this business, working with associates north of the border to sell the oil to American companies at huge markups.

In 2009 a federal court convicted an American businessman of helping to funnel $2 million in petroleum products stolen from Pemex by a Mexican cartel, eventually selling it to a Texas chemical plant owned by the German chemical company BASF. The chemical company claims never to have known where the products came from.

Cartels are also moving into the market in pirated goods in Latin America. The market used to be dominated by terrorist groups like Hezbollah and Hamas, who operated in the triborder area of Argentina, Brazil and Paraguay. Now the field is being overtaken by Mexican cartels, which already have so much control over the sale of pirated CDs, DVDs and software that many legitimate companies no longer even bother to distribute their full-price products in parts of Mexico.