THE BLOG
01/20/2015 10:26 pm ET Updated Mar 22, 2015

Don't Rush the Marijuana Breathalyzer Into "Zero Tolerance" States

As a criminal defense lawyer, I've handled a few DUI cases in my time. Still, the last thing I want is to share the road with an impaired driver. DUI defense isn't about supporting drunk or drugged driving; it's about making sure the legal system runs correctly.

Trust me, I'm all for finding ways to accurately identify and eradicated impaired driving. I'm just not so sure the criminal penalties we have in place are the way to reach that goal. If our current system of license revocation and jail time were enough to stop drunk driving, we wouldn't have the following statistics regarding DUI and repeat offenders:

  • Nearly 30 million people each year admit to driving under the influence.
  • More than 10 million admit to driving under the influence of illegal drugs.
  • In 2012, more than 1.2 million people were arrested for DUI--a small fraction of those who admit to driving while impaired.
  • Estimates show that nearly one-third of those arrested for DUI are repeat offenders.
Again, if our system was truly attempting to eradicate DUI, rather than simply penalize (and prosper from) it, there would be a much lower recidivism rate. We wouldn't see people with 16, 18, or even 25 DUI convictions.

But now, law enforcement has unveiled a new tool in an attempt to combat DUI: the marijuana breathalyzer.

If I felt for one minute that this tool would return results that show, to some level of scientific certainty, when an individual is driving under the influence of marijuana and also help change the way DUIs are treated and prosecuted in the United States, then I'd be first in line to support it. However, I suspect the marijuana breathalyzer may ultimately do more harm than good.

Researchers at Washington State University are developing a portable breath test designed to detect the presence of THC, a metabolite of marijuana, in a driver's system. No surprise there, as Washington is one of the states which recently legalized recreational marijuana use.

According to one of the state's local newspapers, the News Tribune, approximately 25 percent of all blood samples collected in DUI arrests in the state came back positive for THC in 2013, the first full year after voters legalized recreational marijuana.

With a quarter of all DUI arrests arguably related to marijuana, it seems reasonable that law enforcement would look for a way to quickly determine whether a driver was, in fact, high while driving. However, there are some significant problems with using a portable test to determine the presence of THC.

Among the biggest concerns is the "zero tolerance" policy for drugged driving in some states, including Oklahoma. In these states, a person can be charged with DUI per se for having any detectable amount of THC in his or her system.

Consequently, a person could be criminally charged for driving under the influence days or even weeks after he or she used marijuana--long after he or she was under any influence of the drug and when his or her driving would likely be unimpaired by the past drug use.

In Washington, the per se limit for driving under the influence of marijuana is 5 nanograms of active THC per milliliter of blood (5 ng/mL). However, where this level is set at zero, the presence of a drug's metabolites (not its effect on a person's ability to drive safely) is grounds for criminal conviction. There is a difference between being under the influence and having residual metabolites of a substance in your system.

So what happens when we throw in a portable breath test to detect driving under the influence of drugs (DUID)?

Let's say you spent the weekend with friends in Colorado, and before you came home to your zero-tolerance state, you took advantage of the legal marijuana available to you. On your way home the next day, you are stopped for a burned-out tail light. On the thinnest pretext, police say they suspect impaired driving and ask you to perform a breath test. Knowing you are sober, you agree to the test.

To your surprise, the test shows THC in your system, and you are arrested and charged with DUID--despite being in no way impaired by the drug.

Better yet, imagine the same scenario for a cancer patient who uses medical marijuana to alleviate the pain and nausea caused by the disease and its treatments. Such a person could easily be arrested and criminally charged after a marijuana breath test, despite legally using the drug to treat a medical condition, and despite being unimpaired by the presence of THC in his or her system.

Regardless, the National Highway Transportation Safety Administration's (NHTSA) own research shows that low levels of THC in a person's blood stream have little to no effect on a person's driving. While acute marijuana use--within a couple of hours of driving--can cause impairment, past drug use has little to no effect on driving ability. Note the following statistics the California chapter of the National Organization for the Reform of Marijuana Laws (CA NORML) provides from the NHTSA studies:

  • Although 7-20% of drivers in fatal accidents have THC in their systems, 70-90% of those drivers also have alcohol in their systems. In those cases, the primary cause of the accident is alcohol impairment, not marijuana impairment.
  • Blood samples from 1,882 drivers killed in fatal accidents between 1990 and 1991 showed alcohol in the systems of more than half the drivers, but THC in the systems of fewer than 7% of drivers.
  • An NHTSA study entitled "Marijuana and Actual Driving Performance" reports that the effects of driving after marijuana use are "relatively small" compared to drunk driving, and that cannabis use is not "profoundly impairing."

Marijuana use is not always non-impairing, though. Drivers with a THC concentration greater than 5 ng/mL--the amount determined for DUID in Washington--have a significantly higher accident rate than drivers with no THC in their systems. However, drivers with trace amounts of THC--enough for a DUID arrest in zero-tolerance states--do not show any greater risk of accidents in comparison to drug-free drivers.

It seems likely that a pot breathalyzer would increase the number of DUI arrests; however, those arrests will often be drivers who pose no greater risk on the roads than teetotalers who never indulge. While the number of arrests will increase, it will be unlikely that a THC breath test would actually get impaired drivers off the road.

In fact, in many states, the marijuana breathalyzer would ultimately put unimpaired drivers in jail instead.