It is hard to believe that it has been almost ten years since I first wrote about the supposed phenomenon of “green tongue” from marijuana smoking. Back in 2010, I explained how the Washington Court of Appeals issued an opinion questioning the notion that marijuana smoking caused “green tongue.” The court indicated that it was “skeptical of the accuracy” of the trooper’s methods of recognizing marijuana use. Since then, I am sorry to say, courts have been a lot slower to shoot down or reject this sort of nonsense.

Take the recent unpublished case of People v. Berrara for example. In that case from last January, the court of appeals unquestioningly accepted the opinion of a justice department “expert” and stated “The effects of marijuana use may include a lack of convergence in the eyes, dilated pupils (but not necessarily), increased pulse rate, bloodshot eyes, and, in some cases, a green tongue.” Or consider the recent decision by a federal court in Green v. Laden. In that case, the court ruled that observation of a “green tongue” together with raised taste buds and the presence of marijuana amounted to probable cause.

So in the last ten years since I wrote that blog post, Washington and Utah are the only states with decisions by an appeals courts which shoots down this green tongue myth. For lawyers that don’t have a court decision backing up common sense on this subject, it is best to use the government’s own publications against them. For example in the 2007 Drug Recognition Expert Instructor Manual, it is suggested “Point out that there are no known studies that confirm marijuana causing a green coating on the tongue.” (Cannabis, Section XXI, Page 6).

The truth is it is quite hard to tell when someone has been smoking marijuana or if they are under the influence of that drug. Nonetheless, the police are tasked with enforcing new marijuana DUI laws that have per se limits for THC / blood content. These new laws have come about as a result of many states decriminalizing the possession of marijuana. Legislatures feel that in order to prevent more impaired drivers, the police need to draw a tough line on marijuana DUI. But since it is difficult to spot these drivers, it often comes down to vague and unscientific criteria like the myth of the green tongue.

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