While the violence continues to rage in Mexico, there are some who believe the escalation of violence is based on decades of scientific literature. In a recent AP report, this belief was backed by a new study.

A review of more than 300 international studies dating back some 20 years has determined that when police crack down on drug users and dealers, the result is nearly always an increase in violence.

Conducted by researchers at the International Centre for Science in Drug Policy, this study finds that when communities get tough on crime, black market profits subsequently increase, prompting fierce battles in an effort to control the lucrative trade. In addition, if powerful and successful drug bosses are eliminated, more brutal and less sophisticated criminals generally step in.

"Law enforcement is the biggest single expenditure on drugs, yet has rarely been evaluated. This work indicates an urgent need to shift resources from counterproductive law enforcement to a health-based public health approach," said Gerry Stimson in the AP report. Stimson is the executive director of the International Harm Reduction Association.

In cases of history repeating itself, consider that in the United States, murders shot up when prohibition on liquor was enacted as well as during Colombia’s crackdown on its drug gangs in the 1990s. As in the past, when President Felipe Calderon took over three years ago and declared a war on drugs, violence within Mexico escalated.

The intensification of drug law enforcement resulted in increased rates of drug market violence in 87 percent of studies reviewed. A number of studies within the report found that violence increases as a result of power vacuums created when police kill or arrest top drug traffickers. Not one of these studies showed a significant decrease in violence.