The debate over cannabis policy has always had everything to do with immigration.

The fruits of a Tijuana marijuana seizure

The American war on marijuana has a villain problem in California. After 14 years of legalized medical cannabis, which has had the unintended consequence of turning nearly every news article about pot into an opportunity for light humor, the face of the drug’s trade has softened considerably. The only real public menace left in the state’s pot economy—the last scourge worthy of old-school drug-war tactics like helicopter drops and raiding parties—comes in the form of Mexican “cartels,” the crime syndicates that grow pot deep inside California’s public lands and sow hellish violence and mayhem south of the border.

Now the dreaded cartels are at the center of the debate over Proposition 19, next Tuesday’s historic referendum on whether California should legalize marijuana as an adult recreational drug. Advocates say that ending prohibition would be the most effective way to beat the Mexican drug rings. A legal marijuana industry, they argue, would undercut the crime syndicates on price and quality and cripple their business. Opponents of Proposition 19, meanwhile, point to the cartels as the true, inevitable face of the drug trade, arguing that the syndicates will only change their tactics and become more violent if the ballot initiative passes.

 Either way, the debate over legalization sounds eerily familiar. Indeed, as the drug war recedes in California, it appears to be returning to its roots. Like the Tax, Control, and Regulate Cannabis Act of 2010, the earliest moves to outlaw cannabis took place at the state level—in California, no less. And like today’s movement for legalization, the push to ban marijuana revolved around fears of Mexicans.

The idea of prohibition first took hold around the time of the 1910 Mexican Revolution, which drove waves of poor immigrants north into the Western United States. Along with their willingness to pick beets and cotton for pitifully low wages, the newcomers brought a penchant for smoking a peculiar sort of cigarette. At the time, cannabis was virtually unknown as an intoxicant among the Anglo-American population, writes Dale Gieringer, the California state director of the National Campaign for the Reform of Marijuana Laws. Aside from a few accounts of hash houses in New York and travelers who had visited the hashish-loving regions of the Middle East, there is next to no record of pot’s recreational use in America before the 20th century.

Criminalizing marijuana, then, was a way of criminalizing Mexicans: a kind of stoner’s Jim Crow. And state lawmakers who favored the policy weren’t exactly shy about their agenda. “All Mexicans are crazy,” said one Texas legislator during the floor debate over marijuana criminalization in his state, “and this stuff is what makes them crazy.” Or as an advocate of Montana’s first anti-marijuana law said in his state legislature: “Give one of these Mexican beet field workers a couple of puffs on a marijuana cigarette and he thinks he is in the bullring at Barcelona.” California’s 1913 law against pot—one of the first such statutes in the nation—banned “preparations of hemp, or loco-weed.”

Prohibition of marijuana finally went federal in 1937. In a little-remarked, exceedingly brief congressional hearing held to discuss the proposed Marihuana Tax Act, Federal Bureau of Narcotics Director Harry Anslinger—who once said that “the primary reason to outlaw marijuana is its effect on the degenerate races”—testified that marijuana caused in its users “insanity, criminality, and death.” As the late historian Charles Whitebread recounts, that official testimony enjoyed a strange afterlife over the next few years, as a series of defendants in sensational murder trials walked off with insanity pleas, claiming they had done their vile deeds under the influence of the obscure drug “marihuana.” Moral panic ensued—as did the drug’s prevalence as something other than a trick legal defense. “Ironically,” writes Gieringer, “it was only after marijuana had been outlawed that it began to become popular.”

Before long, Americans’ taste for marijuana far exceeded that of their neighbors to the south. Today, only 3 million Mexicans say they smoke pot. By contrast, 25.8 million Americans say they have done so within the past year, most of them members of the Anglo-American majority. (On the list of Stuff White People Like, marijuana is No. 33, behind microbreweries but ahead of TheDaily Show.)

And yet Mexico has always managed to play a major role in America’s relationship with weed, just as Latinos have always managed to bear more than their share of the drug war’s aggression. For years, Mexico was the dominant source for all pot smoked in the United States. Then in 1975, the Mexican government, using equipment donated by American drug warriors, sprayed the marijuana fields of the Sierra Madre Mountains with Paraquat, an herbicide deadly to humans. Contaminated pot entered the American supply, which made Mexican dope about as popular as English beef was during Britain’s 2001 outbreak of hoof-and-mouth disease. This helped establish the hippie stronghold of Northern California as the new capital of marijuana production, which in turn encouraged the Mexican cartels to get out of the smuggling game and relocate their gardens to Humboldt and Mendocino. Today, vast Mexican “guerilla grows” colonize the inner reaches of California’s state and national forests, supplying the low end of the marijuana market.

This summer in Northern California, amid all the heady talk of legalization, incidents of violence on public lands between police and guerilla growers reached the highest levels in recent memory. Five growers, all Latinos, were shot and killed by law enforcement officials. But whether these casualties were foot soldiers of the Sinaloa Cartelor simply hired hands working for an American employer is nearly impossible to tell. Because cartels operate somewhat like terror cells (or labor-trafficking rings), even the guerilla growers who fall under arrest often have no idea who their real employers might be.

In fact, many Northern California locals who grow marijuana say they don’t believeall the reports of Mexican cartels deep in the woods: They argue that, more often than not, references to the syndicates are just police hype and overdiagnosis—propaganda meant to keep the marijuana business as scary as possible in the waning days of prohibition. (In an age of stoned-senior-citizen bingo nights, every bogeyman helps.)

Of course, people in the border regions of Mexico don’t have the luxury of entertaining doubts about the cartels’ reach. There, the crime syndicates could hardly be scarier, with a death toll that has reached 28,000 since 2006. Last week, after the Mexican government seized and destroyed 134 metric tons of marijuana, 27 people were killed in Tijuana and Juarez in apparent retaliation. * Earlier this month, during a conference to promote investment in Tijuana, two headless bodies were found hanging from a bridge a few miles away. The most heartbreaking calls for legalization come from within Mexico itself, where the evils of prohibition have exacted the largest human toll.

At the same time, it’s important to realize that the campaign for Proposition 19 is, in part, a fight for control over a hugely lucrative industry. The gentrified segments of the trade want to seize control over the industry from its criminal segments, which frequently happen to have both Mexican labor and Mexican management.

As I have written elsewhere, if Proposition 19—or some successor legislation in 2012—should pass, the marijuana industry stands to grow, prosper, and consolidate. But in the process, it will probably end up trading one form of illegality for another. We could see big pot operations open up in the Central Valley, and the once-outlaw hippies of Mendocino and Humboldt catering to busloads of Japanese tourists with a Napa Valley of marijuana. But in a world of tighter profit margins and higher taxes for growers, the laborers tending these crops will likely be the same people who work virtually every other field in California agriculture: undocumented laborers from the land of Acapulco Gold.

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Correction, Oct. 28, 2010: This article originally referred to “134,000 metric tons.” If that were true, this one drug bust would have accounted for almost three years’ worth of global marijuana production. (Return to the corrected sentence.)