A new year brings a new drug law - and the need for a new drug test

One of the biggest stories kicking off this new year is the execution of the Colorado law legalizing marijuana. The historic ruling went into action yesterday to much fanfare, some dubbing the momentous occasion “Green Wednesday”. The day went off without a hitch, with police officers and state officials on-hand to make sure the crowds lining up to be the first to buy bud didn’t get too rowdy. However, one of the biggest controversies stemming from the law is not the purchasing of marijuana itself, but what smokers will do with it when they need to get home.

Driving under the influence is a serious concern for the new law, and Colorado and Washington have struggled with how to police driving while high. Breathalyzer tests can easily be used to detect alcohol levels in the blood, but the presence of other types of drugs are typically tested for using blood or urine screens — something made a little more difficult at roadside checkpoints. Additionally, marijuana has one of the longest half-lives of any drug, and traces of the substance can be seen for up to a month after last use. This means that a driver could test positive for cannabis without actually having smoked weed for several weeks.

Police officers in Los Angeles, where recreational marijuana use is still illegal, are attempting to tackle at least one of these problems by using saliva swabs to test drivers immediately for the presence of illicit drugs. The LAPD rolled out the initiative in time for New Years Eve, using the tests to check for cocaine, cannabis, amphetamine and methamphetamine, benzodiazepines like Xanax, and opiates like heroin, methadone or prescription painkillers at roadside checkpoints throughout the city. The saliva samples work like a blood test, testing the plasma for the active component in the drug (THC in the case of cannabis). They are less accurate than standard urine screens and have a smaller window for detection, but they are being looked at to use in a pinch in drug DUI stops, providing an empirical justification for bringing someone in for additional testing.

The development of U.S. drug laws to more sensible harm-reduction policies from the draconian war on drugs seen over the last several decades is a revolutionary shift. However, balancing public safety with personal rights will be an ongoing struggle, and, needless to say, all eyes will be on Colorado and Washington in 2014.

Dana Smith

PhD student in Experimental Psychology at the University of Cambridge