Data requested by the AP from the Vermont Forensic Laboratory indeed shows that more drivers are being tested — undergoing blood screenings for drugs, including marijuana.

While some police believe the increase in 2018 shows more people are using cannabis and driving since legalization, other observers say the rise is at least partially due to the expansion in and emphasis on police training in such stops.

MONTPELIER — In the first year that recreational marijuana was legal in Vermont, the number of drivers arrested by state police for impaired driving who had THC in their systems more than doubled, according to state police data.


The rise in testing is due to a combination of factors, including officers getting better at recognizing drug impairment, said Trisha Conti, director of the lab.

“It might just be that officers are getting better at recognizing, it might just be because there are more officers on the road, there’s more DREs (drug recognition experts) than there used to be, so it’s a combination of a lot of things,” Conti said.

About 12 million drivers nationally, 4.7 percent, reported driving under the influence of marijuana in 2018, compared with 20.5 million, 8 percent, who reported driving under the influence of alcohol, according to a new report from the Centers for Disease Control and Prevention.

Vermont currently has 54 officers who are certified drug recognition experts, Vermont State Police Sergeant Jay Riggen said. The number has stayed at about the same level for three years and is up from 35 in 2015, Riggen said.

And other officers are getting trained in Advanced Roadside Impaired Driving Enforcement, a short course aimed at helping officers become better at detecting impaired drivers.

Since Colorado legalized recreational pot in 2014, becoming one of the first states to do so, the number of drug recognition experts has increased from 129 in 2012 to 214 in 2018, and thousands of officers have gotten the advanced roadside training, according to the Colorado Division of Criminal Justice Office of Research and Statistics.


In 2016, the Colorado State Patrol made about 300 fewer drunken- and high-driving cases than in 2015, but the percentage of cases involving marijuana rose to 17 percent of the total in 2016, compared with 13 percent in 2015 and 12 percent in 2014, according to a report from the Rocky Mountain High Intensity Drug Trafficking Area.

In Vermont last year, 324 people were given blood tests for drugs, and 187 had Delta-9 THC in their systems, according to the data provided by the Vermont Forensic Laboratory. That’s up from 201 tested for drugs and 93 showing THC in 2017, and 191 tested and 91 having THC in 2016, according to the data.

The number of Vermont crashes in which the driver tested positive for marijuana rose from 34 in 2017 to 41 in 2018, while the number for 2019 was at 20 as of Dec. 12.

Drug impairment is determined by a roadside investigation that leads police to seek an evidentiary blood test. Unlike alcohol, there is no legal marijuana limit for driving and,according to Conti, the blood tests for drugs do not indicate impairment; they show the presence or absence of something at the time the blood was drawn.

“Impairment is usually demonstrated by observations by the officer, the behavior, the actions that the operator is showing. The test result itself is just kind of supporting evidence of what that officer had observed,” she said.


Matt Simon, New England political director of the Marijuana Policy Project, points out that it’s unknown from the statistics themselves whether any of those drivers was actually impaired by THC.

“A trace amount is enough to show up on a test, and the drivers may have been drunk and/or using opiates, etc.,” he said by e-mail.

In fact, police are seeing more drivers using both alcohol and cannabis or cannabis combined with other drugs, such as opioids or anti-anxiety medications, Riggen said.

But, he noted, small amounts of marijuana that by themselves may not impair someone can become impairing when combined with other chemicals.