Can Portable Breath Analyzers Measure THC Levels?

Posted by Moe Ahmad | Nov 18, 2019 | 0 Comments

In June of 2019, Governor JB Pritzker signed into law a bill that legalizes recreational marijuana use for adults 21 years of age and older. When it goes into effect on January 1, 2020, adults can legally possess up to 30 grams of cannabis and 5 grams of cannabis concentrate.

The law also allows for those with medical marijuana cards to grow up to 5 plants. Those who aren't qualifying patients under the Compassionate Use of Medical Cannabis Pilot Program Act, cannot cultivate their own marijuana; they must purchase it from a licensed seller.

Driving Under the Influence of Marijuana

Although under the new law, adults will be able to legally possess and consume marijuana, it will still be illegal to drive under the influence of it. In Illinois, it is unlawful for a person to get behind the wheel if they have a THC level of 5 nanograms or more.

Roadside Testing of THC Levels

The problem law enforcement faces is how to test for the level of THC – the psychoactive ingredient in marijuana – in a person's system.

Before an officer can arrest someone for driving under the influence of marijuana, they must have probable cause to do so. With alcohol, officers can administer a breath analyzer test on the side of the road to determine the individual's blood alcohol concentration (BAC). However, such devices don't currently exist to determine how much marijuana a person has in their system.

Various companies are working on developing technology to measure THC levels, but defense attorneys a weary of the accuracy of the results. Attorney Moe Ahmad told the Chicago Tribune that he “anticipated a heated discussion about the devices.”

THC Levels and Impairment

When a person ingests marijuana, THC binds with receptors in the brain, which can impair driving-related abilities such as:

  • Reacting quickly to objects on the road
  • Attending to driving tasks
  • Staying in one lane
  • Driving at the posted speed limit

The interesting thing about marijuana is that it can stay in a person's system long after they consumed it. Unlike alcohol, THC gets stored in fatty tissues and can continue to be released for up to 30 days after being ingested.

According to a report released by the National Highway Traffic Safety Administration (NHTSA), some tests of the presence of marijuana could produce false-positive results. If a person is pulled over on suspicion of driving under the influence, test results could indicate that they have the substance in their system even if they did not recently consume it.

Additionally, devices that measure THC levels may indicate that the individual has an unlawful amount in their system, but, as the NHTSA notes, that might not correspond with actual impairment. The agency reported that “peak THC level can occur when low impairment is measured, and high impairment can be measured when THC level is low.”

The NHTSA stated that the alternative to chemical tests for THC levels is psychomotor tests of impairment. Law enforcement could use these methods to establish probable cause.

In some states where marijuana has been legal for a while, police departments have also employed Drug Recognition Experts (DREs), who are trained to look for various signs that might indicate that a person was driving under the influence of marijuana.

The tests DREs run could include:

  • Measuring blood pressure
  • Taking the person's temperature
  • Recording the individual's heart rate
  • Tracking eye movements and pupil dilation

Get Legal Representation from Ahmad Law Firm

Because conducting roadside tests for THC levels is difficult, and the amount in the body might not correlate to actual impairment, it's possible that, when the new recreational marijuana use law goes into effect, you could be charged for a DUI even if you didn't recently consume the substance. If you need legal representation in Arlington Heights, our attorney can provide effective counsel. We will fight hard to protect your rights and seek a favorable outcome on your behalf.

Schedule your free consultation today by calling us at (847) 791-2294 or contacting us online.

About the Author

Moe Ahmad

Attorney Mohammad (Moe) Ahmad received his Juris Doctor Degree from Western Michigan University, Cooley Law School. As a skilled trial lawyer and former prosecutor of the...


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