Decapitation is popular among War on Drugs advocates. You cut the head, and perhaps the neck or even part of a shoulder while you are at it, and the "cartel" is done with as a national security threat.
Former Drug Enforcement Administration Administrator Robert Bonner has argued in Foreign Affairs that this was a key lesson Mexico has to learn from Colombia's success: "Removing the kingpin and his potential successors is the death knell for such organizations." It is quite clear that Mexico has taken note.
Now, note the proviso Bonner introduces in his analysis: "In Colombia, the objective was to dismantle and destroy the Cali and Medellín cartels--not to prevent drugs from being smuggled into the United States or to end their consumption. Indeed, there are still drug traffickers in Colombia, and cocaine is still produced there, but compared with the old cartels, the trafficking groups there today are smaller, more fragmented, and far less powerful--and, most important, they no longer pose a threat to Colombian national security. From a law enforcement perspective, the problem in Colombia today is manageable. The United States must accept that the goal in Mexico is similar: the destruction of the large Mexican cartels, nothing more and nothing less."
Here is the key: national security is the goal, NOT drug trafficking or even public security. This is also how Columbian President Santos put it when he visited Mexico in August: a matter of national security, that has been essentially dealt with as the country now only confronts "minicartels." Violence remains a problem, however, as Colombia's "manageable" public security problem today means 32 murders per 100,000 people, vs Mexico's 18. As I pointed out recently, Eduardo Guerrero Gutierrez has shown how the fragmentation of drug trafficking organizations is in fact a major driver of violence. As to drug trafficking, a recent analysis from the US Customs and Border Protection shows that the killing of drug lords has no bearing whatsoever on the amount of drugs that crosses the border.
So, once again, the beauty of decapitation is in the eye of the beholder and depends on what she wants: national security for the US, public security in Latin America, or effective decrease in drug smuggling. And the problem is: you have to choose.