A cautionary note on the rush to legalize marijuana


by Dan Lucas

I have recently been following Cliff Kincaid’s look at how the media underreports the correlation of marijuana and high-profile violent acts, including the marijuana user who was sentenced recently for shooting at President Obama and at the White House back in 2011.

I first came across a heavy marijuana user being involved in high profile violence while reading the Sheriff’s report on the December 2012 tragedy at the Clackamas mall.

Since then, I have run across other recent examples of marijuana use related to high profile violence (the list below includes Clackamas mall):

  1. January 2014 Mall in Columbia (Maryland) shooter Darion Aguilar admitted his marijuana use
  2. In the April 2013 Boston Marathon bombing, both Tsarnaev brothers were heavy marijuana users.
  3. At the Clackamas Town Center shooting in Oregon in December 2012, the shooter was a chronic marijuana user – a toxicology report showed that he had used cocaine and marijuana prior to the shooting. The Sheriff’s office reported he had been smoking marijuana just before the shooting. The killer smoked marijuana between 1:30am and 3:00am, and again at 3:00pm – immediately before heading to the Clackamas mall where he started shooting at around 3:30pm.
  4. The July 2012 Aurora, Colorado theater shooter, James Holmes, was reported by the NY Post and UK Telegraph to be a marijuana user and told police he had taken Vicodin before the shooting.
  5. Oscar Ramiro Ortega-Hernandez who shot at the White House in November 2011, not only had a semiautomatic rifle when he went to the White House, he also had a case. “A document in the case says that he was determined to express ‘anger towards the government regarding the continued criminalization of marijuana.’ He claimed marijuana ‘made people smart,’ the document said.” The New York Times referred to Ortega as “the lazy kid who used to smoke too much dope.”
  6. Tucson massacre suspect Jared Loughner was known to smoke marijuana (it kept him from being able to join the Army) – the January 2011 Tuscon shooting is where Rep. Gabrielle Giffords was shot.

What struck me is that the media seems to have a very different standard of reporting about any connection to marijuana than they do with certain types of firearms, like the AR-15. As I said to Accuracy in Media “there is a persistent selective and distorted presentation of information. For example, the use of an ‘assault rifle’ will be given huge focus and attention, but the role of marijuana will be marginalized, if reported on at all.”

The fact that some individuals involved in high profile violence are also marijuana users is in no way any kind of proof that marijuana use causes violence. Just as with guns, there are far more people who use marijuana without any incidents of violence. But still, why the double standard by the media? Why is the media so reluctant to look at any possible problems with legalizing marijuana but they are not at all reluctant to aggressively go after gun rights, which are explicitly protected in the U.S. Constitution?

In addition to favorable coverage and non-coverage by the media, marijuana legalization is also well funded. Funding that includes the money given to the Oregon legalization effort (New Approach Oregon) by the Drug Policy Alliance, which has billionaire George Soros on its board. As Willamette Week noted, “This time, the national funders—notably, hedge-fund billionaire George Soros—who helped the Drug Policy Alliance pass legalization in Colorado and Washington, have come to Oregon in a big way for 2014.” And even before this latest push, the marijuana lobby helped elect our current Oregon Attorney General – they gave more than two hundred thousand dollars to Ellen Rosenblum’s campaign. More recently, the Oregon Cannabis Industry Association participated in a fundraiser for state Sen. Floyd Prozanski (D-Eugene).

So, OK, the media supports legalization, legalization has plenty of funding and it has a few key politicians in its pockets. But none of those are good reasons to rush legalization. None of those are reasons not to do some reasonable due diligence.

Even notable voices from the left caution against the rush to legalize marijuana. Former U.S. Rep. Patrick Kennedy (D-RI) opposes marijuana legalization and California Gov. Jerry Brown (D) wants to first see what happens in Colorado and Washington, and just last month he asked “how many people can get stoned and still have a great state or a great nation?”

And now back to marijuana use and the connection to some recent high profile acts of violence. I wanted to know if there had ever been any research on marijuana use in relation to high profile violence.

I reached out to John J. Coleman, Ph. D. and President of Drug Watch International, and I shared with him the above six examples and asked about any research that existed.

Here is his reply, used with his permission, which I think contains some really excellent points and information:

Scientists have long studied the links between the consumption of alcohol, stimulants, depressants, hallucinogens (including cannabis), and violent behavior. I recall many years ago seeing studies performed at federal prison hospitals in Ft. Worth, TX, and Lexington, KY, that showed higher rates of violent crimes by admitted cocaine users compared with those for heroin users. Those hospitals closed in the early 1960s. Animal studies show links between certain drugs and violent behavior but we are limited in what we can learn from animal studies. A dear friend of mine for many years who passed away a few years ago, David Musto, MD, published a book titled “Drugs in America: A documentary history.” (New York University Press, 2002) in which he referenced a 1936 article in the American Journal of Nursing that warned that a marihuana user “will suddenly turn with murderous violence upon whomever is nearest to him. He will run amuck with knife, axe, gun, or anything else that is close at hand, and will kill or maim without any reason.” Musto, a professor of psychiatry at Yale University for many years, was describing the near-hysteria that surrounded marihuana use in the 1930s. He believed that it ultimately influenced Congress to pass the Marihuana Tax Act of 1937. The 1936 movie “Reefer Madness” no doubt reflected some of the same sentiment.

Despite the popular belief for many years that pot “caused” violent behavior, scientists even in the 1930s were skeptical of drawing such a connection. In fact, the only witness in the congressional hearings leading up to passage of the 1937 Marihuana Tax Act that differed on this theory was a physician from the American Medical Association. As I remember, he testified that other witnesses that had come before the committee, particularly Narcotics Commissioner Harry Anslinger, had no credentials to attribute complex psychological effects, such as violent behavior, to marihuana use. In fairness, the AMA was not opposed to passage of the Act but simply wanted to go on record noting its objections to the highly speculative and exaggerated testimony of some other witnesses.

I bring this up because even today there’s still a good deal of scientific doubt about drawing a direct link between drug use and violence. If we peel away some of the ideological noise for a moment, I think their skepticism is not without some scientific basis. Here’s why. In order to establish causality, scientists must be able to show that X is a necessary cause of Y and that Y would not occur without X preceding and causing it. Volumes have been written on the principles of causality going back as far as Aristotle and I’ll not venture far into these weeds. I’m sure you get the point. Moreover, as every statistician is taught, correlation is not causation, meaning that simply because two events occur simultaneously does not mean that one “caused” the other. This, I believe, is what’s going on here and why so many scientists, even today, are reluctant to declare that the use of drugs is a necessary cause of violence. I think they feel more comfortable – from a purely scientific perspective – to note the correlation between the two phenomena.

In the six cases that you cite, it would be reasonable for us to assume a correlation between the drug use of the killers and their violent actions. I think even the most skeptical scientist would likely accept such an assumption as reasonable. Whether we can go so far as to state causality, given what we know from the public record about these cases, would be far less certain, mainly, because we do not know if the perpetrators were psychopaths to begin with and would have acted as they did without the influence of their drug use. There are many psychopaths who commit extremely violent acts and who do so without any evidence of past drug use. In these cases, a scientist might say that because Y occurs without the presence or influence of X, that X, therefore, cannot be a necessary cause of Y – in every instance (as causation requires).

Public policy on drug control does not depend upon being able to show causality between drug use and violence or drug use and adverse health or social outcomes. Showing a close linear correlation between drug abuse and these outcomes is sufficient. At least this was the prevailing wisdom in America for more than a century. The adoption of public policy by political whim, as in the case of CO and WA, runs counter to this tradition and may yet prove to be disastrous. In effect, scientific skepticism about causation has been misinterpreted by policymakers and others to mean that when it comes to pot smoking and violent acts, there is nothing but an occasional and rare coincidental occurrence of little importance. This, I feel, is a tragic mistake in judgment. Modern civilization depends in great measure – I would say, overwhelmingly – on correlations rather than causations. For decades, scientists knew that smoking tobacco was correlated with heart and lung disease but only recently, as a result of advances in imaging and biological sciences, were they able to show a direct causal effect of the toxic agents in smoked tobacco at the cellular level. Everything from children’s toys to the air we breathe and the food we eat must adhere to strict regulations to guard against ingesting harmful chemicals that may cause disease. The notion that they MAY cause disease is not evidence that they DO cause disease; in other words, they are related to, but not necessary causes for, disease. This to some may look like causation but it is not, and that’s my point.  

To wrap it up, I am not discounting the possibility that someday scientists will discover a direct link between pot and violence. Until recently, most people were willing to control this drug based on voluminous anecdotal evidence showing the correlation between pot smoking and violence. The cases you cite are prime examples of this. I’m sure there are many more examples, including some that we may never hear about because they are not as bizarre or do not make it into the media.

I did a quick search of the PubMed files at the National Library of Medicine using the Boolean search terms “Marijuana” and “Violence.” I was surprised to see only four academic articles reporting studies related to these terms. I’ve included the abstracts of the four articles below and, as you will see, they address very specific aspects of certain forms of violence and the consumption of alcohol and/or drugs, including marihuana. These authors show correlations between alcohol and drug use and certain types of violent behavior. The last one in the list touches on a core question that challenges all of the research in this topic and underlies some of what I’ve tried to explain above. That question is, how are mentally ill persons adversely affected and driven to violence by their use of drugs? The authors concluded that persons with non-hospitalized schizophrenia-spectrum disorders who abuse drugs are likely to commit acts of violence. This probably explains the actions of some or perhaps all of the killers in the list you supplied. It also should be a warning to policymakers and the public to re-think the idea of legalizing marihuana. Making this drug available to millions of persons who may have non-hospitalized schizophrenia-spectrum disorders can only result in further tragedy and mayhem.

 John Coleman


1. Psychol Addict Behav. 2013 Nov 25. [Epub ahead of print]

The Temporal Relationship Between Alcohol, Marijuana, Angry Affect, and Dating Violence Perpetration: A Daily Diary Study With Female College Students.

Shorey RCStuart GLMoore TMMcNulty JK.

2. J Interpers Violence. 2012 May;27(8):1562-78. doi: 10.1177/0886260511425787. Epub 2011 Nov 11.

The relationship between marijuana use and intimate partner violence in a nationally representative, longitudinal sample.

Reingle JM1Staras SAJennings WGBranchini JMaldonado-Molina MM.

3. J Ethn Subst Abuse. 2008;7(4):404-27. doi: 10.1080/15332640802508028.

Violence-related behaviors among Dominican adolescents: examining the influence of alcohol and marijuana use.

Reid RJ1Garcia-Reid PKlein EMcDougall A.

 4. Crim Behav Ment Health. 2002;12(2):155-68.

The targets of violence committed by young offenders with alcohol dependence, marijuana dependence and schizophrenia-spectrum disorders: findings from a birth cohort.

Arseneault L1Moffit TECaspi ATaylor A.


To read more from Dan, visit www.dan-lucas.com

UPDATE (June 2014): Las Vegas husband and wife cop killers (killed 2 police officers and 1 shopper) – “In 2010 and 2007 [the husband] was convicted of drug dealing and possession charges related to marijuana.”

UPDATE (June 17, 2015): The NY Times had an update on 7-16-2015 on the June 2015 hate-crime shooting of an historic Charleston, SC, black church, where 9 people were murdered. The NY Times reported that the shooter, Dylann Roof, had a history of smoking marijuana, “Even in his youth, Mr. Roof began to exhibit a greater interest in smoking grass than cutting it. At 13, his mother caught him spending $50 he had earned landscaping on marijuana.” The NY Times also noted that earlier this year, he had been caught by police with Suboxone, a prescription drug used to treat opiate addiction, and charged with a misdemeanor.

UPDATE (July 20, 2015): ABC News reported that Chattanooga shooter Mohammod Abdulazeez (who murdered 4 Marines and 1 sailor) was “In a downward spiral, Abdulazeez would abuse sleeping pills, opioids, painkillers and marijuana, along with alcohol,” according to a family representative. ABC also reported  “Three months before the shooting, Abdulazeez was arrested on April 20 — a day celebrated annually by marijuana users — and charged with drunk driving. The arresting officer noted a smell of marijuana in the car.”

UPDATE (October 31, 2015): The killer in a deadly random shooting spree in Colorado Springs wouldsmoke pot for breakfast.” The killer had struggled “with drugs, alcohol and depression.”

UPDATE (November 28, 2015): The NY Times reported that the accused killer at a Planned Parenthood clinic in Colorado Springs went on online message boards to find companions to smoke marijuana with and he used to post on Cannabis.com. The NY Times also reported that the accused killer moved from the Carolinas to Colorado in 2014 with a woman he had been dating for about six years. The first retail marijuana stores opened in Colorado on January 1st, 2014.

UPDATE (December 3, 2015): Elsevier reported that “Several studies have demonstrated that the primary active constituent of cannabis, delta-9-tetrahydrocannabinol (∆9-THC), induces transient psychosis-like effects in healthy subjects similar to those observed in schizophrenia.” Elsevier is a publisher of scientific, medical, and technical journals.