All college students ought to be familiar with the arguments against illicit drug use. They are numerous: the wasted hours, the decline of physical health, the spiral into addiction and the possibility of overdose and death. The effects of illicit drug use are, of course, not limited to the individual user; drug use tears apart families, breaks down friendships and destroys the fabric of communities through the crime and social waste that it inspires.I would venture to guess most American college students acknowledge and accept these arguments against drug use, even the estimated 39 percent of college students who have used illicit drugs themselves. After all, these arguments about “wasted hours,” “addiction spirals” and “broken communities” apply only to the heroin-plagued neighborhoods of America’s inner cities or the rotting Appalachia towns devastated by methamphetamine, right? There cannot be any harm in casually smoking marijuana with some friends, correct? Or so the prevailing narrative goes. But these assumptions are as naïve as they are incorrect. Every time someone uses an illegal substance, he assumes a moral culpability for the effects of this use. This includes moral culpability for enabling and supporting the organizations that deal drugs. And while casual college users obviously understand that their purchase and use of illicit drugs supports the local dealer in the apartment down the street or the room across the hall, their money ultimately supports something far more sinister than the flameout college drug dealers of popular imagination. I am talking, of course, about Mexican drug cartels. Mexican drug cartels are entrenched in the marijuana business; estimates from 2008 suggest 15 to 26 percent of cartel revenues stem from marijuana sales, with the rest coming from cocaine, heroin and methamphetamine. Moreover, a huge percentage of American marijuana is originally from Mexico, and is transported across the border by drug cartels — as much as 67 percent of all American marijuana, according to one 2008 study. It is worth noting that the drive toward American decriminalization and legalization has somewhat loosened cartels’ grip on the American drug market, as seizures of cannabis along the U.S.-Mexico border are down 37 percent since 2011, but presumably this drop in the consumption of Mexico-imported marijuana is largely concentrated in states such as Colorado, where domestic production is rampant. In states such as Virginia, where marijuana production and consumption remain very much illegal, I would imagine chances are high that illegal marijuana is tied to drug cartels. The statistics are even worse for other drugs; if you choose to use cocaine, for instance, chances are upwards of 90 percent that it has traveled through Mexico.Americans support and enable the existence of drug cartels by constituting the largest consumption market for illegal drugs on the planet. The consequences of such American demand are clear and stark. Since 2006, over 100,000 have been killed in drug-related violence in Mexico, including over 1,000 children. The statistics alone fail to reflect the grisly horror of individual killings, such as 193 men and women who were senselessly raped and tortured before being murdered in cold blood in a single 2011 incident. The cruelty and inhumanity of these deeds rivals any of ISIS’s work.Over spring break, I traveled to the U.S.-Mexico border (staying on the Texas side) to volunteer in a refugee clinic for those seeking protection in the United States. I spoke with women who had seen their husbands murdered and who implied that they or their friends were forced to help the cartels even as they sought refuge in the United States. One of the men helping to run the clinic said to me, “The dirty little secret of this whole thing is that the lives of our neighbors to the south would be so much better if Americans could just stop doing drugs.” He is right, and we should to listen. Globalization’s most notable consequence may be that individual actions have concrete impacts on lives across the world. We have the ability to speak with our pocketbooks — every time one of us buys illegal drugs, we are potentially enabling some of the planet’s most sadistic organizations, whether we care to admit it or not. As a final note, there are some who will surely argue that further legalization of marijuana will eliminate Mexican drug cartels from the American marketplace, and will allow Americans to use without having to worry about implicitly supporting truly evil institutions. This may be true, but it scarcely takes the moral burden off of those who use drugs illegally in our present moment. For now, we can quietly take action against cartels by spurning illicit drug use. Hundreds of thousands of lives may depend on it. John Connolly is an Opinion columnist for The Cavalier Daily. He can be reached at firstname.lastname@example.org.