In my last column I stepped in a pile of doo-doo regarding the implications of the April 17 state Court of Appeals decision in People vs. Koon. I said that a strict interpretation of the ruling meant that any medical marijuana patient could not legally drive.

That is not true.

Quite a few medical marijuana activists took me to task about that, most pointedly attorney John Targowski of Kalamazoo. There are several potholes and nuances here that I didn't take into account. In addition, I didn't know about a key 2010 state Supreme Court decision.

Let's back up a moment. People vs. Koon is a Grand Traverse County case in which a medical marijuana patient was charged with driving while impaired because there was THC present in his system. The Court of Appeals ruling read: "... in the motor vehicle code, the legislature has provided a definition of what constitutes being under the influence of marijuana: The presence of any amount ... of marijuana."

This is dicey right off, because nobody has marijuana in their system unless they took a leaf and shoved it directly into a vein. However, because the language of the motor vehicle code and a source I spoke with said the "M" word, I let myself slip and wrote that "marijuana is detectable in the blood for several weeks." That is incorrect and I knew better. 

When marijuana is ingested through smoking, some elements of the substance are released into the bloodstream. Most pertinent to this discussion are THC, CBD and a few dozen other cannabinoids. THC is the cannabinoid at the root of marijuana hysteria because it's the one most directly responsible for the high. Most edible preparations of marijuana involve a process where THC (and probably some other cannabinoids) are infused into butter or oils. Although the Alice B. Toklas recipe called for throwing the plant material directly into a batch of brownies back in the day, marijuana cuisine has moved far beyond that stage.

Here's where the nuance comes in. THC is only present in the blood for a very limited amount of time that varies based upon factors such as how much was in the marijuana to start with. That can vary from about 2 percent (not very potent) to about 35 percent (what some might refer to as "killer weed"). Other factors include how often a person uses marijuana, and, when it comes to testing, whether it is whole blood or plasma being tested and the sensitivity of the equipment being used.

For most people other than chronic users, the body processes the THC within several hours and turns it into the benign metabolite carboxy THC (THC-COOH). Targowski says that's two to 12 hours for most people. But everyday users have THC in their systems most of the time — though this does not necessarily mean they are impaired by it all the time.

THC-COOH, meanwhile, can stay in your system for up to several weeks, and that was enough to get you busted for driving while impaired — until the 2010 state Supreme Court decision in People vs. Feezel. In that case, the court acknowledged that THC-COOH is not a Schedule 1 substance, as THC is. THC-COOH is only a byproduct of your body processing THC and is not psychoactive. 

"Thus, anyone can drive with any amount of THC-COOH, patients or not" and not be legally impaired, Targowski wrote in an e-mail.

Sorry for the false alarm, folks. However, it is also prudent to note that not all law enforcement officers, prosecutors and judges understand the difference between THC and its metabolite THC-COOH. In reaction to the Koon decision, Genesee County Prosecutor David Leyton told the Flint News: "The problem is the active ingredient in marijuana stays in your system for 30 days or longer some times. That's going to make it difficult for medical marijuana users to drive a car."

And he's considered a moderate on the issue of medical marijuana.

So while you may ultimately be vindicated in an appeal, it appears you could well be charged and forced to go through the irritation of having to defend yourself on a DWI charge. It may be helpful to learn what the prevailing opinion in your municipality is.

Despite the prevailing tax-and-regulate-like-alcohol mantra of the legalize-it crowd, alcohol intoxication and its presence in the blood serve as a poor analogy for the THC process. Paul Armentano, deputy director of the National Organization for the Reform of Marijuana Laws, says, "It doesn't make any sense to make per se standards like there are for alcohol. I think there is a lot of misunderstanding. There are people who say we need a breathalyzer test like there is for alcohol. That is not an impairment test. We have a long history of science supporting a blood alcohol level that correlates with impairment. We have all of this science behind drinking and driving; we don't have that science with THC."

Armentano has done a lot of writing on the science about marijuana and has testified in numerous legal cases as an expert witness. 

The research that has been done tends to downplay the role of THC in traffic accidents, particularly in more experienced users. A study reported in a 2010 issue of the journal Pharmacology, titled "Tolerance and cross-tolerance to neurocognitive effects of THC and alcohol in heavy cannabis users," found that: "Alcohol significantly impaired critical tracking, divided attention, and stop-signal performance. THC generally did not affect task performance." They concluded, "[T]he present study generally confirms that heavy cannabis users develop tolerance to the impairing effects of THC on neurocognitive task performance."

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