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Bicycling and Drugged Drivers

Since California first legalized marijuana for medicinal purposes with Proposition 215 in 1996, there has been a growing national movement towards full legalization. In 2012, Colorado and Washington became the first two states in the Union to legalize cannabis for adult recreational use. This November 8, the voters in California will decide whether to join these other states in legalizing pot when they vote on Proposition 64.

Copyright: KarenRoach_123rf.com

Copyright: KarenRoach_123rf.com

All of this means that there is a growing trend toward the legal and social acceptability of cannabis use in the United States, and in California in particular. But greater availability of the drug raises several issues of concern for bicycle safety. Negligent drivers are the greatest threat to bicyclists on the road today. And impaired drivers are more likely to be negligent. We already know this from the dangers presented by drivers under the influence of alcohol and prescription drugs such as opiates and benzodiazapenes. So a rise in marijuana usage may signal an increased threat that all cyclists should be aware of.

This danger raises several interesting legal questions on the criminal and civil front. Here, we focus on the civil aspects of marijuana impaired driving. For instance, how does cannabis work to impair driving? How much is too much? Are there any safe levels? While these questions have not yet been settled scientifically or legally, this series of articles explores what we currently know about cannabis, and points the way forward to how these issues may be resolved over time. The following article focuses primarily on the science of how the different varieties of the THC molecule work on the brain and body. Understanding these basics is essential in any criminal DUI or civil personal injury case involving marijuana consumption and driving.

A Tale of Three THC Molecules

Driving under the influence of marijuana cases present a unique situation because unlike with most other chemical impairment prosecutions there are three different THC molecules, which are tested for after a blood sample has been taken from the suspect. Unlike cases involving alcohol or a pharmaceutical drug, where police are testing for a single substance suspected cannabis users are tested for three: THC, Hydroxy-THC and Carboxy-THC.

There are no scientific studies to date that prove how to predict a true absorption and elimination curve for THC; however, studies have shown that Carboxy-THC can stay in a person's system for up to thirty days. There is no true understanding and agreement about the absorption and elimination of THC in the human body. This presents defense attorneys fertile ground to challenge prosecution evidence relating to a blood test obtained hours after the actual time of driving, under the standards governing scientific evidence set by the Daubert and Frye cases. That is important because THC also known as Delta-9 Tetrahydrocannabinol is the Main Isomer and principal psychoactive constituent of marijuana.

After smoking, the blood concentration of THC spikes and drops dramatically within an hour. When cannabis is ingested orally, there is no significant spike. Within two hours maximum blood concentration is reached, which is far lower than when smoked. The elimination after oral ingestion is gradual over the following ten to twelve hours.

Hydroxy-THC, more specifically 11-Hydroxy-Delta-9 Tetrahydrocannabinol, is the Main Active Metabolite of THC. That means the body converts THC into this metabolic version; Hydroxy-THC, which is active in its own right, but with different effects which are generally not psychoactive. Scientists believe that this may explain the bi-phasic effects of cannabis, such as increased appetite hours after consumption. After smoking cannabis, Hydroxy-THC levels reach their maximum blood concentration within about half an hour and are a fraction of THC levels even at their highest before being eliminated within four to five hours later. After oral ingestion, Hydroxy-THC peaks after about two hours and then is gradually eliminated over the following 12 hours.

The final molecule in the "THC trio" is Carboxy-THC, 11-nor-Carboxy-Delta-9-Tetrahydrocannabinol, is the main secondary metabolite of THC. It is not psychoactive and has a half-life of many weeks in cases of heavy use. Carboxy-THC blood concentration peaks rapidly about half an hour after smoking and may increase a small amount and then gradually decreases as it is eliminated very slowly over many hours, days and weeks. In contrast to THC and Hydroxy-THC, the highest Carboxy-THC levels are reached in the blood stream when cannabis is consumed orally. The peak concentrations are reached within about four hours of consumption and drop by two thirds after ten to twelve hours. In California, Carboxy-THC levels are measured but not used to determine impairment. Unfortunately, for drivers in States with "zero tolerance" presence of Carboxy-THC in their blood, it is sufficient to find them guilty of violating the law of driving under the influence even though it may have been several weeks since they consumed it.

Defense lawyers handling marijuana DUI cases must be familiar with the three molecules and their different absorption and elimination rates, which vary depending on the method of ingestion. The blood concentration of marijuana users peaks, drops, and then can peak again long after the psychological effects have passed. Understanding the science of marijuana chemistry and explaining it to prosecutors, judges and eventually jurors is important to prevent innocent drivers from suffering the consequences of being convicted of driving under the influence just because the police found marijuana in the vehicle after stopping on a routine vehicle code violation.

With the prospect of legalization law enforcement is looking to deal more aggressively with driving under the influence of marijuana cases. Prosecution of these cases will increase and while is more difficult to obtain a conviction in a marijuana DUI in comparison to driving under the influence of alcohol cases, law makers are doing their best to level the field.

Similarly, personal injury plaintiff's attorneys need to be knowledgeable in the science and in this evolving area of law. It is essential for a good attorney to not only understand how marijuana impairment works physiologically, but also track the rapidly changing laws in this area, in order to assist courts in reaching a just result and ensure their clients are compensated for their injuries.

© The Law Firm of Richard Duquette, 2016, All Rights Reserved.

Co-Authored by: Mark Bluemel, Richard Duquette, and Justin Nelson

October 31, 2016