How do Police Test for Marijuana DUI Impairment?

April 03, 2022 by Anthony Riccio

While the personal use of marijuana is now legal in Massachusetts (up to 10 ounces is allowed at home), it is still against the law to drive while impaired using marijuana. 

Given that, it has become an increased challenge for the police to keep up with the nearly 1,000 strains of marijuana sold across the United States – and new strains constantly added onto that. Some help with focus and concentration, some help athletes with their workouts, some help with pain. But there are also strains that cause impairment, which people should avoid while driving.

Law enforcement, however, needs to implicitly prove that one is guilty of driving under the influence. 

What is Considered Impaired Driving by Massachusetts Law?

Impaired driving in Massachusetts is defined in Section 24 of the state’s general code as operating a motor vehicle while under the influence of any intoxicating liquor or drug against the law.

The only differences? For alcohol, there is a specific blood alcohol content level set at .08 percent, but there is not a specific limit for marijuana, which means it is against the law to operate a motor vehicle at any level. There also is no reliable test for marijuana impairment, unlike a breathalyzer or blood alcohol test for drunk driving. 

This makes proving a driver guilty of driving under the influence of marijuana way more complicated. Police and prosecutors need to prove evidence of impairment by a driver’s mental or physical abilities while driving.

How is Marijuana Impairment Tested?

There is no official blood or breathing test for marijuana impairment. Even if a driver’s blood is tested, there is no way to know exactly when it was ingested because the metabolites in marijuana can stay in the blood for weeks after using it. 

Because of that, most officers in Massachusetts use roadside tests to check a driver’s balance, cognition, and reflexes, as well as evidence of use, such as the smell or actual visual appearance of the drug at the scene. 

When a police officer pulls a driver over on suspicion of a DUI or OUI (operating under the influence) in Massachusetts, they will look for evidence of impairment that will support an arrest, which includes:

  • Any driving infractions made by the defendant
  • The defendant’s statements made to the officer at the scene
  • How the defendant performs on field sobriety tests
  • The defendant’s physical symptoms that could indicate intoxication, such as dilated pupils, red eyes, smell on breath, speech patterns, slow reaction time, and more

This evidence and the results from these tests can be used by the arresting officer to testify at trial and prove that the defendant was guilty of DUI marijuana. 

Is There a Way to Defend a DUI-Marijuana Charge?

The arresting officer will usually give a testimony in support of a defendant’s intoxication. There are also some municipalities that call on a DRE, or drug recognition experts, to examine the defendant after a DUI-marijuana arrest and then testify at trial on their findings. Here is where the defense comes in. 

In a recent DUI-marijuana case in Massachusetts, a prosecutor aimed to prove that the defendant on trial was impaired from marijuana while driving, which would make him guilty of DUI, according to state laws. The arresting police officer testified that, based on his observations of the defendant and the field sobriety tests performed at the scene, the defendant was, indeed, high on marijuana. 

The defendant was convicted of DUI, but the criminal defense lawyer appealed, and the DUI conviction was successfully reversed. According to the Massachusetts Supreme Judicial Court, a police officer cannot legally testify that a defendant is high on marijuana based on observations and field sobriety tests. The officer was not an expert on marijuana and how the drug has different effects on people, so his testimony could not support a DUI conviction.

Chemical testing, or a blood test, may be another way the arresting officer attempts to prove a driver’s marijuana intoxication while driving to determine the level or concentration of THC in the defendant’s blood. Results of a blood test, however, are not immediately available and not sufficient enough to prove a driver was impaired by marijuana.

How do Field Test Results Differ from DUI-Marijuana Cases and Alcohol DUIs?

Although subjective, field sobriety tests are typical in any DUI case. And, if the tests have not been recorded by the arresting police officer’s camera, the performance of the defendant is on the officer’s word alone. 

The effects of excessive amounts of alcohol are mainly consistent among a wide range of drivers, which means officers are allowed to testify to support a defendant’s DUI arrest. For DUI marijuana cases, officers cannot testify and convict based on observations they made from the field tests. An officer can share observational facts from the report that was filed, such as a strong smell of marijuana, bloodshot eyes, or slurred speech, but their overall testimony is limited.

Law enforcement and the criminal justice system in Massachusetts are slowly recognizing that there are many layers and variants of marijuana, combined with the timing of the effects and the type of person who has used the drug, that goes beyond science. 

What are the Penalties of a DUI-Marijuana Conviction in Massachusetts?

If a defendant is found guilty of driving under the influence of marijuana, the penalties could include a hefty fine, a jail sentence of varied years, and a license suspension.

In general, first offense penalties could break down to include a driver’s license suspension of 90 days to a year, fines ranging from $500 to $2,000, up to a year jail sentence, a sentenced probation term, and possible court-ordered abuse treatment. Subsequent offenses, of course, will carry stiffer penalties, with a third drugged driving conviction considered a felony.

The prosecution needs to prove the defendant was driving while impaired by a substance to get a conviction.

Hire a Defense Attorney Today

For those facing a DUI-marijuana charge, contact the Massachusetts-based criminal defense team at Riccio Law. We will review the steps of the case and be there every step of the way. We have fought for defendants’ rights in this situation and have won with our honest, aggressive approach for our clients.