Marijuana Field Sobriety Tests Are Not Reliable

There is currently a nationwide discussion about the legality of marijuana. While the federal government continues to debate whether or not marijuana is legal, the state of Arizona has very strict laws regarding purchase, possession, and use of the substance. Only people with medical marijuana card can obtain small amounts of marijuana from approved dispensaries.

While some people may legally obtain and use marijuana in the state, Arizona still does not have a proper means of testing for pot in a driver’s system. The entire country is struggling with this issue. Marijuana DUI law is still evolving given the country’s changing attitudes toward marijuana. With that in mind, our legal office serving the Phoenix, AZ area would like to consider some of the current issues related to field sobriety tests to detect marijuana use.

About Field Sobriety Tests

A field sobriety test is a way for law enforcement to assess the motor skills and decision-making skills of a driver who is suspected to be under the influence of a controlled substance.

The nature of these tests can vary, but they generally involve:

  • Demonstrations of balance, such as standing on one leg or walking a straight line
  • Demonstrations of basic coordination and motor skills, such as touching one’s nose
  • Assessment of mental state, such as reciting the alphabet and simple information
  • Checking the tracking ability of the eyes

Can Field Sobriety Tests Detect Marijuana Use?


There are many problems with field sobriety tests even when trying to determine if a person has been drinking. The effects of marijuana can vary from person to person. Additionally, field sobriety tests are unscientific, and the nervousness of a traffic stop and other factors may contribute to poor performance of simple tasks.

Simply put, field sobriety tests are not a reliable way for law enforcement to determine if a driver has been using marijuana.

Stories in the News About Marijuana Sobriety Testing

These assertions are backed up by stories in the news.

In the state of Massachusetts, for instance the Supreme Judicial Court ruled that field sobriety tests cannot be used as concrete evidence against a driver who is suspected to have been driving under the influence of marijuana.

Law Enforcement Doesn’t Have Reliable Marijuana Testing

While some law enforcement is using special swabs to detect the presence of THC in a person’s saliva, the accuracy of these tests is still up for debate. Blood tests can measure the amount of THC in someone’s system, but again, marijuana can affect people in different ways. Someone may have more than 5 nanograms of THC in their system but function completely normally without any impairment. By contrast, someone with that much THC in their system may not be able to operate a vehicle safely.

How an Attorney Can Help You

At the moment, scientists are still working out a reliable form of testing that is accurate for marijuana DUI cases that also take into account actual impairment. Research is ongoing.

Because of these facts, it’s important to have an attorney on your side who understands the limits and inaccuracies of field sobriety tests when it comes to marijuana DUI cases.

Contact an Experienced Marijuana DUI Lawyer

For more information about your legal rights and options following an arrest for driving under the influence of marijuana, be sure to contact the Law Office of James Novak. We will fight diligently for you during your time of legal need.

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