A relatively new development in Mexico’s ongoing drug wars is the increasingly active role of vigilante groups. That is especially true in Michoacán and other states in the western portion of the country. I discuss that development in a new article over at the National Interest Online.

The initial temptation might be to cheer on the vigilantes. After all, the rise of “self defense militias” indicates that a growing number of Mexicans are now willing to resist the power of the brutal cartels and fight back, if necessary. But for two reasons one ought to resist the temptation to applaud. First, the nature of many of the militias is exceedingly murky. Some of them may even be front groups for rival trafficking organizations seeking to displace the dominant cartel in a particular region.

Second, even in cases where the vigilante groups are genuine anti-cartel forces, the growth of vigilantism is a worrisome sign. It is an emphatic vote of “no confidence” in the government’s ability to maintain order and the rule of law. That is similar to what occurred in Colombia from the late 1980s through the early years of the 21st century. As the power of drug gangs and their radical leftist guerrilla allies surged, frightened and angry Colombians formed right-wing militias in many rural areas. But some of those groups soon became little more than death squads, and for a time, Colombia seemed to be heading down the path toward becoming a failed state. We certainly do not want to see a comparable trend in our next door neighbor.

The rise of vigilantism in Mexico is yet another reminder of the disastrous consequences of drug prohibition. That strategy greatly raises the retail price of a product that a large number of consumers insist on using. Creating such a lucrative black market premium fills the coffers of those willing to defy the law to traffic in that product. And the vast majority of individuals and groups willing to take that path are ruthless criminal elements. Prohibition, in short, empowers and enriches thugs.

Washington’s enthusiasm for and insistence upon preserving an international drug prohibition policy has caused enormous problems for Mexico and other drug-source countries. As the leading consumer of illegal drugs and the most powerful member of the international community, the United States largely determines the direction of policy on this issue. Fortunately, there are signs of changing attitudes on both the domestic and international fronts. Public opinion surveys show that a majority of Americans are now in favor of legalizing marijuana, the mildest of illegal drugs, and such states as Colorado and Washington have already adopted modest legalization measures. Uruguay has gone even further, legalizing not only the possession and use of marijuana but also commerce in that drug.

Uruguay’s course is the correct one. It’s not enough to legalize drug possession—the trade itself needs to be taken out of the hands of criminal syndicates. And if we wish to defund the cartels, abolishing prohibition must apply to all currently illegal drugs, not just marijuana. Our policy makers need to internalize the lesson that prohibition not only does not work, it causes horrific unintended consequences. That was true of America’s foolish crusade against alcohol in the 1920s and early 1930s, and it is true in spades of the current crusade against illegal drugs. The surge of vigilantism in Mexico and the threat of chaos it embodies should spur policy makers to finally recognize that reality.