How powerful had the Mexican drug cartels become by the start of Felipe Calderón’s presidency in 2006?

Mexico’s cartels became especially powerful during the 1980s and 90s. The old cocaine route through the Caribbean had been effectively shut down by Reagan’s Florida Task Force, making the overland route through Mexico more important. At the same time, Colombian capos began paying their Mexican couriers in product, rather than cash. This fattened the Mexicans’ profits, which enabled them to influence more senior public officials, through the traditional means of “plata o plomo”, or “silver or lead”—that is, bribes or bullets.

How effective has Calderón’s five year war on drugs been in reducing drug-related violence and dismantling the cartels?

 It has succeeded in dismantling some cartels. The Beltrán Leyva organisation crumbled after its eponymous leader, Arturo, was killed in 2009. A year later, La Familia Michoacana fell apart when its leader was killed by the police. But each dead kingpin has been replaced by a new one—and the succession-battles have made violence worse, not better. During Calderón’s five years the murder rate has more than doubled. Kidnapping, extortion and robbery have increased steeply too, as the police’s incapacity to deal with their higher workload has allowed cartels to branch out into new lines of business.

What has been the US’s contribution to tackling drug trafficking?

The United States is the main market for Mexican drugs, the main source of Mexican weapons, and the main proponent of the failing ‘war on drugs’. Over 100 years ago Porfirio Díaz, a Mexican President, said, “Poor Mexico: so far from God, and so close to the United States.” The relationship is not all bad—legal trade across the border is worth hundreds of billions of dollars a year to both countries. But on security, Mexico gets a bad deal. The Mérida Initiative, America’s contribution to Mexico’s fight against the cartels, is worth less than $500m a year, equivalent to about 3% of Mexico’s federal security budget.

What reforms are necessary to start to reduce the corruption endemic in the Mexican police forces and government?

Mexico has plenty of police, but they are badly organised. Whereas Colombia has a single national force, Mexico’s officers are split into more than 2,000 municipal forces, plus 31 state forces and a separate federal police. They do not trust each other. Mr Calderón has enlarged the federal force, which is reckoned to be the least corrupt. But his attempt to bring all police under a single national command has been blocked in Congress. Officers might be harder to corrupt if they were better paid, but no government can match the wages offered by the narcos. Better prosecution of corrupt officers would be a more effective deterrent.

How do the presidential candidates propose to tackle organised crime if elected in July?

Presidents serve only one term, so Calderón is out. His centre-right National Action Party has put forward Josefina Vázquez Mota, who says she would enlarge the federal police from 40,000 to 150,000 officers. Andrés Manuel López Obrador of the left-wing Party of the Democratic Revolution says he would create a single national policeforce and withdraw the army from the streets as soon as possible. One last thing. Cocaine is expensive because the price covers the cost of murder. Until it is legal, you cannot buy it in Oxford without contributing to someone’s slow death in a Tijuana cellar.

Tom Wainwright is the Mexico City bureau chief of The Economist