Driving Under the Influence of Marijuana

March 2, 2014

Although some states have begun legalizing marijuana for both medical (such as New Jersey) and recreational use (such as Colorado), much research has not yet been conducted on the effects of driving while under the influence of marijuana.  Answers to important questions such as how dangerous it is, how to test for impairment due to marijuana, and how the risks compare to driving while intoxicated, have been slow to reach the general public. 

In 2007, a study found that 12% of drivers stopped on highways across the nation on Friday and Saturday nights had been drinking.  Of those driver, 6% of them tested positive for marijuana.  In a study published in 2012 by the journal Pscyhopharmacology, only 30% of people that were under the influence of marijuana failed the standard field sobriety test.  According to the study, the ability of field sobriety tests to identify drivers under the influence of marijuana depends largely on whether or not the driver is accustomed, or has built a tolerance, to being stoned.  In other words, while a 21-year-old who is intoxicated by alcoholic for the first time and a hardened alcoholic will both exhibits signs of intoxication, the same is not true for marijuana.  While a driver that smokes marijuana for the first time may very well fail field sobriety testing by exhibiting signs of being under the influence of marijuana, a driver that smokes marijuana on a regular basis and has built up a tolerance to the drug may not.  In another study, 50% of the less frequent marijuana smokers failed the test.

Many people, moreover, do not realize that DUI laws apply to marijuana.  Some driver’s even believe that they are better drivers while they are high.  The evidence suggests, however, that this is not the case.  It is clear that marijuana impairs driving ability.  Several researchers have come up with the same estimate: a twofold increase in the risk of an accident if there is any measurable amount of THC in the bloodstream.  The estimate is low, however, compared to driving under the influence of alcohol.  Another study found that 20-year-old drivers with a blood-alcohol content of 0.08 percent (the legal limit) had an almost 20-fold increase in the risk of a fatal accident compared with sober drivers.

According to some researchers, the difference in impairment due to marijuana and alcohol can be explained by the fact that stoned drivers has different deficits and, as a result, drive differently from drunken ones.  While drunken drivers tend to drive faster than normal and to overestimate their skills, the opposite is true for stoned drivers.  This fact has lead some experts to believe that public resources are better spent fighting drunken driving.  Stoned driving, they say, is best dealt with by discouraging people from mixing marijuana and alcohol — a combination that is even riskier than alcohol alone — and by policies that minimize marijuana’s risk on the road.

Still, others have little doubt that smoking marijuana impairs driving.  Operating a motor vehicle is a complex, attention dividing task.  Marijuana hinders your ability to divide that attention.  Studies have shown that marijuana use can cause drowsiness and an altered sense of time.  It also inhibits people from performing divided-attention tasks.

Police have been trained to spot the effects of marijuana on drivers.  Many of those signs are the same as intoxication due to alcohol: poor balance, slurred speech, and watery eyes.  Other signs, like a green tongue or the inability to cross one’s eyes, are not shared with alcohol.   Officers also look for the odor of marijuana.  Moreover, police often stop stoned drivers for the same reasons: swerving across lines, failing to maintain a proper speed, or failing to move when the light turns green.

If you are arrested for driving under the influence of marijuana, contact an experienced DUI attorney today.  In New Jersey, is any amount of marijuana in your blood or urine will establish that you were driving under the influence.  Also, while New Jersey allows the use of medical marijuana under certain circumstances, it is still illegal to drive after such use if your ability to safely operate a vehicle has been impaired.  Contact the Law Office of Randolph H. Wolf today for a free consultation.

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