Cannabis Field Testing?
Updated: Aug 28, 2018
As more states are moving toward legalization, the question is posed -- what will law enforcement do in regards to cannabis-use and driving? Currently, officers who suspect a driver to be under the influence perform a series of roadside tests as well as a sample of either blood or saliva. They utilize technology that measures detectable THC in the blood and oral fluids. Some would argue that these current measures are intrusive. These methods have often been found to be inaccurate because while they do detect use, they do not indicate the recency. They can provide false positives where the person may have ingested cannabis within that week or month, but not necessarily in the recent past (2-4 hours).
The introduction of newer technology has allowed law enforcement to administer tests that show use potential in frequent users up to 4 hours detected, and infrequent users detectable 2 hours after smoking. THC and alcohol are metabolized differently. Unlike alcohol, which distributes evenly throughout the body through water that is present in our blood (Blood Alcohol Content, BAC), THC has to be carried around by transport proteins. Unfortunately, it is not as easy as replicating technology. “Picture cutting a raisin into a trillion parts and trying to detect one of them.” So, the traditional breathalyzer used to read BAC wouldn’t work for a number of reasons; one being the vapor pressure of THC is very low, it is predicted to be approximately 100 million times less than ethanol vapor pressure.
Hound labs and Cannabix Technology have released their own breathalyzers. Hound Labs out of California boasts that they have a dual marijuana/alcohol detector, while Cannabix out of Canada also has their own marijuana breathalyzer. When someone blows into the breathalyzer, it will indicate shortly after whether there is alcohol, THC or both in the person's system. Since THC is only present in someone's breath during that peak two-hour window, the driver is considered impaired when it's detected. The breathalyzer would then display "Warning" if THC is detected and "Pass" if it is not. New technologies such as these will aid in fairly assessing whether a person is in fact intoxicated at the time of testing. The next step will be figuring out what a legal limit should be. We wait to see what happens next. Safe Driving!