With the legalization of marijuana for recreational and medicinal uses across the country, police and legislators are scrambling for accurate devices that can detect a person’s impairment for driving under the influence of marijuana. Most law enforcement agencies rely on observation and specific cognitive and field balance tests by certified drug recognition experts (DRE). However, none are scientifically accurate to detect the level of impairment.

There is a company that claims to have developed a portable device that can be used at a roadside motor vehicle stop to detect the presence of THC, the psychoactive active ingredient in marijuana. The device maker claims that it can detect whether a person has smoked pot within the prior two hours, a window that many experts consider the peak impairment time frame. If true, this would be a major breakthrough for law enforcement because the other standard tests – blood, saliva or urine – require days for the results.

Given the difficulties in reliably and accurately detecting the presence of THC in breath molecules – measured in parts per trillion rather than parts per thousand for alcohol – it is likely that this device will not be approved for use in most states for many years to come. In addition, even if the device can accurately discover the presence of THC, it cannot calculate the amount of THC consumed. Given that there is no consensus as to what amount or level of THC constitutes functional impairment, it will be up to each state to pass laws as to what standards are acceptable for driving while impaired for marijuana. So far only seven states have set legal standards as to how much THC in a person’s system is considered impaired. Yet many scientists believe those standards are not scientifically reliable.

What seems indisputable, however, is that states with legal marijuana experience higher incidents of accidents with drivers under the influence of alcohol and marijuana. What is still unknown is what role the use of marijuana played, if any, in these higher accident rates. This is the challenge for scientists and legislators to determine now that the use of marijuana is steadily being decriminalized.

In the interim, the experts’ advice is simple – have a designated driver, call a cab, Uber or Lyft – if you have used marijuana before driving.

Robert Stahl, and his firm, Stahl Criminal Defense Lawyers aggressively defend individuals charged with complex federal and state crimes, including drug crimes. Founder Robert G. Stahl is recognized as one of the top criminal defense attorneys in the NY/NJ area for his skills, knowledge and success. To contact the firm, call 908.301.9001 for the NJ office and 212.755.3300 for the NYC office, or email Mr. Stahl at rstahl@stahlesq.com.