Marijuana is now becoming a concern for people everywhere.
Charter Oak High School

Commentary: ‘Weeding’ out the suspects

Drinking and driving has been a problem for a long time. Driving under the influence causes accidents to happen often with fatal outcomes and puts anyone on the road in danger. Sobriety tests exist to determine whether someone is drunk and have made roads a bit safer for drivers. A new problem has risen in recent times.

With the recent legalization of marijuana, more and more people are openly smoking and even driving while smoking marijuana. Driving under this influence also causes problems for drivers. New methods to determine whether a driver is under the effects of marijuana are being explored.

Detecting marijuana is slightly different from detecting alcohol levels.

“Unlike alcohol and other drugs, blood and urine tests can detect marijuana in a person’s blood stream several weeks after the drug has been consumed, making it especially difficult for a method of detection that proves a person consumed forms of THC within hours of driving,” stated

Tetrahydrocannabinol, THC, is the active ingredient in marijuana and the substance that is looked for when testing for driving under the influence of marijuana.

The main way to detect marijuana is through a field sobriety test. The field sobriety test looks for the same signs as those under the influence of alcohol.

“California law enforcement officials rely heavily on field sobriety tests when deciding whether or not to arrest a person who is suspected of driving under the influence,” says The three main tests done for those who are pulled over are the horizontal gaze nystagmus test, the walk and turn test, and the one-leg stand test.

In California, if an officer believes that an individual is under the influence of marijuana, he has consent to get a blood, breath, or urine test from the suspect. The urine test and blood test are uncommon, and they are also not very precise. The tests do not determine whether marijuana was consumed within the last few hours.

“That just tells you somebody has smoked,” says Margaret Haney, a professor of neurobiology at the Columbia University Medical Center. “But you don’t know if they smoked an hour ago or if they smoked a week before or two weeks before.” Breathing tests, on the other hand, cannot, yet determine whether someone has consumed marijuana.

Another possibility of testing for marijuana is a saliva swab test.

“The test is roughly eight-minutes long and uses a person’s saliva to detect THC, crystal meth, methadone, cocaine, and several other prescription medications,” according to

Conflicting reports exists to the accuracy of the swab test. There can be traces of some drugs in the saliva up to three days after the consumption of the drug, making this process an unreliable source of evidence to prove whether someone was driving under the influence of marijuana.

As of now, there are no reliable and proven ways of testing for marijuana in drivers. Not only drivers, but also pedestrians, need to be wary of potential dangers on the road.