Stoned driving is up in Colorado, report says, but reliable statistics still elusive
October 3, 2016
Marijuana-related traffic deaths have been on the rise in Colorado, increasing by 62 percent since recreational marijuana was legalized in 2013, according to a report released last month by the Rocky Mountain High Intensity Trafficking Area, a federally funded law enforcement group. The group, however, has been criticized as biased against the marijuana industry, and forming direct links between car crashes and marijuana use can be difficult.
According to the report, average yearly marijuana-related traffic deaths were up 48 percent from 2013 to 2015 compared to the three years prior. The report also notes that in 2009, 10 percent of drivers in all traffic fatalities tested positive for marijuana, but by 2015 that figure had doubled to 21 percent.
Proponents of legal marijuana, however, have questioned the group's methodology, accusing it of bias against the marijuana industry.
"This is a group that campaigned against Amendment 64 and has a very clear interest in making things look bad," said Mason Tvert, communications director for the Marijuana Policy Project. He also said that overall DUI rates have gone down over this same time period.
The RMHIDTA obtained its data by cross-referencing CDOT crash data with coroner reports, flagging fatalities as "marijuana-related" whenever the drug was mentioned in a toxicology report. As the report notes, however, that doesn't necessarily prove marijuana was the cause of the crash, or if other factors such as alcohol impairment were involved.
The Colorado State Patrol has been cautious in its assessments, noting that their data on driving high dates back only to January 2014—a short timeframe to draw conclusions from. Of the 4,546 DUI tickets troopers wrote last year, 347, or 7.6 percent, involved only marijuana.
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"We have seen an increase, to be certain," said Trooper Josh Lewis. "But it is very early, and we don't know, for instance, if that increase is because more people are using or if our officers are getting better at detecting it."
All CSP troopers are trained in field sobriety testing, but around the time marijuana was legalized, the agency added Advanced Roadside Impaired Driving Enforcement (ARIDE) certification to its regimen. More than fifty of the agency's troopers have also undergone a weeks long drug recognition expert course, said Lewis.
Over the limit, but not under arrest
THC—the active ingredient in marijuana—can stay in a person's system long after its impairing effects have worn off, meaning that a heavy user who tests positive after a crash may not have been impaired at the time.
And while Colorado's legal limit for impairment is 5 nanograms per milliliter of blood, the accuracy of that measure for determining impairment is disputed.
"The available evidence does not support the development of an impairment threshold for THC which would be analogous to that for alcohol," said Jeff Michael, with the National Highway Traffic Safety Administration. He explained that while a blood alcohol content of 0.08 is firmly associated with four times greater risk of crashing, similar data for THC isn't yet available.
"Overall, it's a relatively arbitrary number," said Tvert. "It's based on various studies, but they just wanted to get a number."
Driving high has always been illegal, but it wasn't until Amendment 64 passed that the 5 nanogram limit was voted into law. Some, like Tvert, suspect that this was a response to political pressure and designed to insulate lawmakers against renewed concerns over impaired drivers.
Unlike the 0.08 blood alcohol content limit, the THC standard only creates a rebuttable assumption—not definitive proof—that a person was intoxicated. Given the uncertainty surrounding what exactly constitutes marijuana impairment—and how differently the drug affects people—this can make consistent enforcement difficult.
At a recent candidate forum in Idaho Springs, District Attorney Bruce Brown said that the way the way the 5 nanogram limit is currently set up makes enforcement difficult because it can be argued away in court.
"Some of these people at 16 nanograms may not be under the influence, but I think it's a trade-off. If you want to be a regular user of marijuana, give up your driver's license," he said.
Brown said he would like to see a consistent standard that, like blood alcohol content, would mean an automatic violation of the law, not something you could argue in court.
"If you were of the opinion that you should be able drive above 0.08 blood alcohol because for you that's not impairment, I would say give up your license and take public transportation," he said later in a phone conversation. "Lets treat marijuana like alcohol and find a standard."
What that standard might be, however, is unclear, and people like Tvert caution against treating THC concentrations like blood alcohol content.
"There's a lot of research being done right now, but the issue is marijuana doesn't affect people as consistently as alcohol does and can be present at high levels in people that aren't impaired," he said.