Legal and scientific experts sharply question proposed crackdown on drugged driving

Critics say bill would roll back marijuana legalization, undermine judicial independence

Marijuana in a jar.Lane Turner/Globe Staff/file

Governor Charlie Baker is putting new pressure on the Massachusetts Legislature to finally pass his proposed crackdown on drugged driving, instead of letting the measure — initially filed in 2019 — again die in committee.

During a recent legislative hearing, a number of his administration’s highest-ranking public safety officials urged lawmakers to advance the bill, arguing it would save lives by making it easier for police and prosecutors to detect, arrest, and convict drivers high on marijuana and other substances.

But as state legislators chew on their testimony, prominent experts are stepping forward to warn the plan is fundamentally flawed.

They say it risks sweeping up law-abiding drivers by forcing courts to consider the results of a questionable roadside impairment evaluation — and automatically suspending the licenses of those who refuse to participate in follow-up blood tests. Critics also question whether the Legislature has the power to require that judges accept the testimony of police officers trained in the technique, which in the absence of reliable “pot breathalyzer” technology leans heavily on their subjective observations.

“It’s junk science to the nth degree,” Nancy Gertner, a retired federal judge and senior lecturer at Harvard Law School, said in an interview. “The Legislature has no business mandating who or what can be admitted into court — especially testimony that doesn’t meet evidentiary standards. It’s preposterous, and challengeable on any number of grounds.”

Baker has named his refiled legislation after Thomas Clardy, a state trooper struck and killed by a vehicle during a traffic stop in 2016. The vehicle’s driver, a medical marijuana patient, was later convicted of involuntary manslaughter and other serious charges, but acquitted of driving under the influence of cannabis.

State Police took photographs of a heavily damaged unmarked cruiser during their investigation of an accident on the Massachusetts Turnpike east of exit 9 on March 16, 2016. State Police trooper Thomas Clardy, who was injured in the crash, later died.Paul Kapteyn/Worcester Telegram & Gazette via AP/file

Proponents say the bill would close gaps that can allow people who drive while impaired by cannabis or other drugs — including prescription medication — to escape accountability. Its centerpiece is an expansion of the “drug recognition expert,” or DRE, protocol, which aims to train police officers so they can identify whether someone is impaired and by what substances.

In addition to several familiar balance and attention tests adapted from roadside evaluations of drunkenness, the 12-step DRE process includes measurements of heart rate, temperature, and blood pressure, plus observations of the suspect’s pupils, muscle tone, “attitude, coordination, speech, breath and face.” Baker’s bill would further subject suspected stoned drivers to a blood test for metabolites of THC, the primary active ingredient in marijuana, and require state courts to recognize DRE-trained officers as experts.

“It’s simple: You can’t drive safely when you’re impaired,” Terrence Reidy, a former prosecutor and the secretary of the state’s Executive Office of Public Safety and Security, told lawmakers at the mid-December hearing. “This legislation will improve community safety and advance good criminal justice policy.”

Reidy, who noted that AAA and Mothers Against Drunk Driving support the bill, insisted the DRE and blood test system is “rigorous.” But in interviews, scientists, defense attorneys, and other experts assailed the procedure as little more than pseudoscience.

One of their central objections is that tests for THC metabolites only indicate marijuana use in recent days or weeks, not active impairment at the time of the test. Recent studies have found that, unlike with alcohol, there is no reliable connection between impairment and the amount of THC in someone’s blood; heavy and novice marijuana consumers can have substantially different responses to identical doses of the drug, and some medical cannabis patients even show cognitive improvements.

Policymakers “are so desperate to have an impairment metric for cannabis that’s equivalent to alcohol, but unfortunately, it’s much more complex,” said Dr. Staci Gruber, a longtime cannabis researcher at McLean Hospital. “People are convinced somehow that higher frequency and magnitude of use automatically equals higher levels of impairment, which is just not true.”

Meanwhile, many of the symptoms evaluated under the DRE protocol, such as a racing heartbeat or high blood pressure, just as easily could be explained by anxiety or numerous other physiological causes unrelated to drug impairment, critics said. That shortcoming is even more pronounced in the absence of individual-level baseline testing that would offer a point of comparison to the results of a roadside test.

“Even given hours and hours with subjects in the lab, it’s incredibly challenging to detect and quantify impairment specific to a certain substance, much less multiple substances,” Gruber said. “If we’re going to mandate this and make claims that DREs can reliably and in a valid way identify those who are impaired while driving, we should have clear, empirically sound evidence showing that — and I don’t think we do.”

Skeptics also argued that DRE observations are likely subject to the same biases that permeate much of the criminal justice system.

Given longstanding racial discrepancies in traffic stops, prosecutions, and sentences, “the notion that police officers after a few weeks of [DRE] training could disentangle bias from their observations is absurd,” Gertner said. “It opens the door to selective enforcement.”

She predicted the bill could lead to prosecutions of sober drivers who are simply availing themselves of the state’s legal medical and recreational cannabis markets — but flunk a THC blood test after being deemed stoned by DRE-trained officers who smell their breath.

“You’re effectively criminalizing the same conduct” explicitly legalized by voters in 2016, Gertner said.

Public defenders and criminal defense attorneys also are objecting strenuously to the bill.

Nathan Tamulis, a forensics attorney at the state’s Committee for Public Counsel Services, testified at the hearing that the measure was too expansive and exposed drivers taking practically any kind of medication to legal risk.

John Amabile, the president of the Massachusetts Association of Criminal Defense Lawyers, noted there was no evidence of an uptick in stoned driving since marijuana was legalized, and argued that prosecutors already have the ability to call officers as witnesses and hold drugged drivers accountable.

A Globe review of State Police data in November found no significant increase in drugged driving charges since marijuana legalization; 83 percent of recent citations for operating under the influence concerned alcohol, and police officials said most of the remaining drugged-driving charges were related to opioids, not pot.

Along with Gertner, Amabile compared DRE tests to other types of evidence that were once common in courts but have more recently been discredited, such as blood splatter analyses and the testimony of supposed bite mark experts.

“That junk science led to the unjust convictions of people on very serious offenses, and before we start admitting any kind of scientific evidence, we need to ensure it’s reliable,” he said. “This is a fake emergency pushed by the same people who are upset that cannabis was legalized.”