So it’s always interesting when leaders from such countries disagree with the premise — as, in my experience, they usually do.

On Thursday I put the question to Costa Rica’s president, Laura Chinchilla Miranda, who was in town mostly to talk trade and investment (and to speak Saturday at commencement ceremonies at Georgetown University, where she is an alum).

“The problem with the drug issue is that sometimes people look for very simple responses,” Chinchilla replied.

Marijuana legalization would simply impel the gangs to concentrate on harder drugs, she said. “You will always have organized crime looking for what is illegal, in order to profit from it,” she said.

And the more drugs you legalize, the more people will use drugs. “You’ll have competition. People will want to sell.” So, she said, any move in that direction would have to be preceded by careful preparation, especially of the health system. And that would be as true for Mexico as for the United States, because it’s also simplistic to view one country as exclusively producing or transshipping and another as exclusively using.

“All of the countries are suffering from the whole chain,” Chinchilla said. Costa Rica is safer and suffering less than some other nations, the president said, but knows that it is not immune from the “contamination” of drugs. It is beefing up its police (Costa Rica has no army), shoring up the transparency of its courts and other institutions (to ward off drug-fueled corruption) and emphasizing prevention.

Still, casting doubt on legalization as a solution does not mean that Chinchilla is satisfied with current anti-drug approaches. Despite tremendous investment and effort over the past 15 years, she said, “We cannot say the situation is better now than it was in the past.”

In particular, Chinchilla said, the countries of the region “have to move from law enforcement to a more integrated approach”-- including emphasizing prevention and treatment — and have to focus on illegal trade from north to south (of guns, for example) as well as south to north.