Did Marijuana Kill Michael Brown?
In a radio interview on August 18, a self-identified friend of Darren Wilson's reported that the police officer suspected Michael Brown was under the influence of drugs the day Wilson shot him to death in Ferguson, Missouri. "He really thinks he was on something," the friend said, "because he just kept coming." Wilson made no mention of that theory during his grand jury testimony on September 16, although he did liken Brown to a "demon" and Hulk Hogan, descriptions reminiscent of the evil and strength sometimes attributed to illegal drugs.
One challenge for anyone pushing a pharmacological explanation of Brown's alleged behavior: Despite speculation that he was on PCP, marijuana is the only drug that was detected in his blood. Kathi Alizadeh and Sheila Whirley, the assistant county prosecutors who presented evidence to the grand jury, did what they could with pot, raising the possibility that Brown had smoked enough to experience "paranoia," "hallucinations," and maybe even a "psychotic episode." They planted that idea in jurors' heads mainly by presenting a toxicologist's misleading testimony about the amount of THC in Brown's blood and the possible effects of large doses.
The toxicologist testified that Brown's blood contained 12 nanograms of active THC per milliliter, a level that he said indicated Brown had consumed cannabis in the previous two or three hours. That contradicted testimony by Dorian Johnson, the friend who was with Brown when Wilson shot him. Johnson, who said he was with Brown all day, testified that they had planned to get high (hence the cigarillos that Brown stole from a convenience store) but never got around to it. Despite the blood test results, Johnson could be telling the truth. Daily marijuana users have been known to register 12 nanograms or more when they get up in the morning, and they may even perform competently on driving tests at that level.
In a 2013 experiment sponsored by KIRO, the CBS station in Seattle, one volunteer, a medical marijuana user, tested at 16 nanograms when she arrived but nevertheless completed a driving course satisfactorily and continued to do so until she hit 58.8 nanograms. A subject in another 2013 experiment, this one sponsored by KDVR, the Fox affiliate in Denver, was already at 21 nanograms when he arrived, even though he had not consumed any marijuana that day, and reached 47 after he smoked some pot. He performed fine on a driving simulator at both levels.
Alizadeh noted that Colorado and Washington both have set five nanograms as the cutoff for drugged driving. But as the experiments by KIRO and KDVR indicate, that standard is highly problematic, treating many regular users as impaired even when they're not. The fact that Brown's THC level was "over twice" this arbitrary number, as Alizadeh emphasized, does not necessarily indicate he was too stoned to drive, let alone that he had consumed enough marijuana to precipitate a psychotic break.
To give you a sense of how misleading the discussion of marijuana-induced psychosis was, consider this exchange between Alizadeh and the toxicologist:
Prosecutor: Could you experience the hallucination and/or the psychosis if you had a high enough dose of THC?
Witness: If you got a high enough dose, you could have a psychotic episode into hallucinations, yes.
Prosecutor: Now, in this particular case, when you tested the blood and you got 12 nanograms per milliliter for the delta-9-THC, do you consider that a high dose?
Witness: OK—
Prosecutor: What conclusions did you make from that?
Witness: Well, you have to put things in perspective. This was a very large individual. I think he was about 300 pounds. So for concentration of 12 nanograms in a large person, that shows it was a large dose. In a small person, say like 100 pounds, to get to 12 nanograms wouldn't take a lot. A single joint could easily do that. But when you talk about a larger body mass, just like drinking alcohol, larger persons can drink more alcohol because they have the receptacle to hold it.
By conflating dose with blood concentration, this exchange implies that 12 nanograms of THC per milliliter will make a large person crazier than a small person, which makes no sense. If smoking a single joint can raise a 100-pound person's THC concentration that high, and if 100-pound people who smoke a joint do not commonly behave the way Wilson claims Brown did, why should we believe marijuana helps explain why Brown is dead?
The prosecutors spent considerable time insinuating that Brown had consumed cannabis in the form of the concentrate known as "wax," even though there does not seem to be any evidence that he did and even though it would not matter if he had. If the issue is Brown's level of intoxication, the amount of material he burned to achieve it is irrelevant. The testimony about wax looks like an attempt to exoticize a familiar drug that people do not usually associate with demonic rage or Hulk-like strength.
Then again, marijuana may be exotic enough as far as the prosecutors are concerned. "You explained that the Delta-9-THC has a psychoanalytic effect?" Alizadeh said at one point. "Psychoactive," the toxicologist corrected her. Later Whirley asked, "Could this amount of THC that was found in the blood be—is it possible that someone [could be] ingesting that amount on a regular basis and not be dead?" The toxicologist explained that "marijuana really isn't lethal." Unless you smoke it before getting stopped by a cop, I guess.
