As I’ve mentioned in past posts, law enforcement has a major problem in determining whether a driver is under the influence of, say, marijuana. Actually, there are two problems…
The usual procedure is to take a blood sample and have it analyzed for the presence of marijuana — or, more accurately, for the presence of the active ingredient, tetrahydrocannabinol, or THC, in the blood. However, this does not tell us whether the subject is under the influence to the extent that he is impaired — that is, "unable to safely operate a motor vehicle". The simple fact is that no reputable laboratory or governmental agency has been able to establish what the critical level of THC is that constitutes impairment. Unlike with alcohol, where there is a presumption of intoxication at a level of .10% percent alcohol in the blood, we simply don’t know what amount of marijuana causes what level of impairment.
Second problem: the presence of THC does not tell us when the marijuana was consumed — and whether it is still active in the system. The fact is that metabolites can remain in the blood — inert and thus not causing any impairment — for weeks after being initially taken. A driver could be stopped a week after smoking a joint and a blood test would show him positive for THC.
Despite this, governmental agencies and law enforcement continue to come up with new, quick and easy technology to "detect" levels of impairment in drivers. And politicians, in their desire to look "tough on drunk driving" to voters, continue to fall over themselves in passing laws enabling these new weapons in the "War of Drunk Driving"…the most recent being a new device which supposedly permits cops to pull a driver over, take a swab of saliva from his mouth, and have it instantly analyzed at the scene for marijuana and drugs.
California Looking at New Drug-Detecting DUI Technology
Sacramento, CA. May 11 – California lawmakers are considering a proposal that would give cops permission to use technology that identifies drivers under the influence of marijuana, cocaine and other drugs.
Assembly Bill 1356 changes California law to state that any person driving a motor vehicle has given their consent to chemical testing of his or her blood or oral fluids. Under the measure, law enforcement officers are then authorized to use a new device that can detect drugs in someone’s system using a swab of saliva.
The DDS 2 Mobile Test System was developed by Alere and is reported to have a 90 percent accuracy rate, according to the company. The device screens the saliva sample and determines in a matter of minutes whether the driver has taken amphetamines, cocaine, marijuana, methamphetamines or opiates…
Sounds great: A new gizmo that can quickly tell a cop if a driver is under the influence of, say, marijuana. For a more detailed discussion of the flaws in this new DDS2 Mobile Test System, see my post from April 27th, "California Proposes New Law to Allow Roadside Marijuana Test".