Law enforcement currently detects THC, the active ingredient in marijuana, through a blood or urine test. This poses several problems when someone is pulled over for driving under the influence, however.
THC dissolves in fat and remains in the body for long periods. Frequent users may feel perfectly normal yet test for a high amount of THC. In Colorado, this has led to significant debate over whether there is any measurement like blood alcohol concentration that can provide a guideline for impairment.
Seven states currently have legal guidelines regarding the level of THC that may impair driving ability. In Colorado, that level is 5 nanograms of THC per milliliter of blood. If a driver is found over that threshold then they are presumed to be under the influence of marijuana.
New device claims to accurately measure THC on breath
According to National Public Radio, a California company is claiming to have created an accurate device that can measure both THC and alcohol on a driver's breath.
This has long been a difficult feat. Unlike alcohol, which is measured in parts per thousand, THC is far less concentrated. Being able to detect THC on a person's breath has proven extremely difficult.
If it works as intended, the new tool could become a staple for police across the nation.
Marijuana on breath could indicate recent use
With marijuana, detecting THC on the breath is a better indicator of recent use than alcohol. If marijuana is on a person's breath, it is likely he or she smoked within the last several hours, according to Hound Labs CEO Mike Lynn.
They are piloting the device this fall, and hope to sell it to police forces across the country in 2019.
Meanwhile, the debate over how much marijuana is impairing, and how long that impairment lasts, continues.