Why no marijuana breathalyzer will actually catch high drivers

This article looks at why so-called marijuana breathalyzer tests can’t actually determine intoxication.

On January 1, 2018, California became the latest and by far the largest state to legalize the recreational use of marijuana. While legalization has the support of most Californians, many have raised concerns about whether legalization will lead to an increase in DUIs involving pot. One particular area of concern is that while driving while intoxicated is obviously illegal, actually enforcing that law is difficult. That's because, as Wired reports, marijuana works very differently in the human body than alcohol does, which makes any current marijuana "breathalyzer" effectively useless at determining whether a driver is high or not.

Why pot breathalyzers don't work

Ever since a number of states began relaxing their marijuana laws, a number of companies have promised to develop a breathalyzer-like device for detecting marijuana in drivers' system. Most of these devices promise to help police officers quickly detect whether a not a driver is high by using a chemical threshold. Most such devices determine this threshold by measuring how much THC, the psychoactive compound in marijuana, is present in the driver's body, similarly to how alcohol breathalyzers can quickly determine a person's blood alcohol concentration.

However, the problem is that THC, unlike blood alcohol concentrations, is a very unreliable measure of determining whether or not a person is impaired. THC can remain in a person's body for up to a month after marijuana was last ingested and long after any impairing effects of the marijuana have worn off. Furthermore, a habitual marijuana user can build up a tolerance to the drug, meaning that even if their THC levels are high they may still be able to drive a car safely. An infrequent user, on the other hand, may have a very low THC level and be far too impaired to drive. Other factors, such as body weight and how much food a person consumes, can also affect how impaired that person will be.

Enforcing marijuana DUI laws

As the Santa Rosa Press Democrat notes, California does not set a THC threshold at which a person is considered too high to drive, which is likely the most sensible approach given that THC levels have very little to do with impairment. Instead, prosecutors rely on observations made by police officers as well as tests conducted by specially trained drug recognition officers. While such an approach addresses concerns about using an arbitrary THC threshold, it also raises other concerns, such as the reliability of the officer's determination that a suspect may be high as well as the verifiability of any test conducted by drug recognition officers.

Criminal defense law

As the above article shows, legalization of marijuana in California may certainly be the right step forward, but it is leading to complex legal issues. That means that those who have been charged with a drug-related crime, such as driving under the influence of marijuana, should reach out to a criminal defense attorney today. An experienced attorney can help clients either fight against the charges or help them mitigate the fallout and sentencing that a conviction may lead to.