By Darren Smith, Weekend Contributor
States do have the legal authority to establish presumptive impairment levels, that is a measurable quantity of a substance sufficient to establish an element of DUI. In fact while the present presumptive alcohol level in the United States for ordinary drivers is .08, states have established .04 for commercial vehicle driving and some states have .02 for those under twenty one years of age who violate analog status offenses that do not define impairment as an element.
Now, the American Automobile Association’s Foundation for Traffic Safety cited a study that differences between individuals can be wide and greatly varied regarding impairment at a set blood THC level. While some drivers show obvious signs of impairment at low levels of THC blood concentration, other persons can have greatly elevated readings and show no outward appearance of signs of DUI.
In the case of driving impairment by reason of ethyl alcohol concentration, decades of various studies have shown a direct relation between blood alcohol levels and DUI impairment. Studies on THC impairment are alas comparatively novel. There is however a level of tolerance of course with nearly all intoxicating substances, some marked, which of course presumptive alcohol concentration level statutes fulfill the required element for DUI prosecution.
On of the first generally used presumptive DUI alcohol concentration level in many states for a reading of breath was .10 grams of alcohol for each 210 liters of breath. Further studies recommended the presumptive level be reduced to .08. The federal government then pressured the states to lower the presumptive levels.
The Recreational Marijuana states: Washington; Colorado; and Montana, place the presumptive THC level at 5 nanograms per milliliter of blood.
The AAA findings suggested, in part, that performing direct comparisons with alcohol impairment is problematic.
Since the time required to administer a THC blood test is often two hours or more after the suspected driving, as compared to breath tests, levels of the intoxicant can drop rapidly. Conversely the study cites that infrequent users of marijuana tend to metabolize THC faster than heavy users, who might in fact carry loads of THC well in excess of 5 nanograms but show no outward impairment. AAA’s position was that such testing and enforcement leads to an unequal treatment of persons when a presumptive level is used.
Another AAA study, released in 2015, found that fatal collisions involving drivers who recently used marijuana had doubled in Washington since the state legalized individual possession in 2012: from eight percent to seventeen percent. Most of the drivers, according to the study, had alcohol or other drugs in the blood at the time of the collision.
In the view of your author there are some weak points in this study. AAA stated that the drivers were not necessarily impaired by marijuana nor were at fault in the collisions. Additionally, in Washington a mandatory blood draw is triggered when a driver is suspected of reckless driving or DUI that results in a fatality. A search warrant also might be obtained or a driver can voluntarily submit to a blood test in lieu of a breath test. There are opportunities where no impairment would be indicated in a test where a positive level of THC is found in a driver’s blood. This is especially evident in cases of Reckless Driving not involving DUI. It usually is the case where alcohol is the primary intoxicant, yet even a minor level of THC will flag the test for this study.
Moreover, arrests for DUI where marijuana impairment prior to legalization was in some jurisdictions uncommon or rare. But, these certainly rose due to the wider availability. It is however difficult to accurately measure a history of non-collision involved DUIs where both marijuana and alcohol are might have been contributory to impairment. Standard practice in DUI enforcement is when alcohol is suspected as being over a presumptive level, despite the presence of other drugs, the de facto rule is to process the suspect only for alcohol impairment due to time and resource constraints. Since only the alcohol tests are required for a DUI element that is all that needs to be satisfied. Thus, historical usage and levels of THC concentration will be difficult to quantify.
By Darren Smith
Source: The Olympian
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