With an anticipated increased legalization of recreational marijuana in the Northeast, town police expect that they may encounter more motorists illegally driving under the influence of marijuana.

Recently, recreational marijuana became legal in Massachusetts. The state legislatures in Connecticut and New York are considering similar legalization.

In 2011, the possession of less than one-half ounce of marijuana was decriminalized in Connecticut, reducing a person’s initial possession of marijuana from a misdemeanor to an infraction. In 2012, the Connecticut legislature approved the use of medical marijuana.

The federal government, however, considers marijuana possession illegal, classifying it as a Schedule One “controlled substance.”

Newtown Police Patrol Sergeant Matthew Wood, who is the police department’s drug recognition expert, (DRE), said that as legal marijuana becomes more widely available in the Northeast, police may encounter more cases in which motorists are driving while intoxicated or impaired by marijuana.

Local police statistics show a drop in DUI incidents in Newtown, with 63 such cases reported in 2018, compared to 79 incidents in 2017. In 2016, there were 54 such cases, with 70 incidents in 2015. The statistics do not include DUI arrests made by state police, who patrol Interstate 84 and make a significant number of such arrests there.

Sgt Wood estimates that somewhat less than half of all the DUI arrests made by town police stem from drug intoxication, rather than alcohol intoxication. The applicable state law pertains to “driving under the influence of alcohol and/or drugs.”

In 2014, all local police patrol officers received 16 hours of specialized training intended to help them spot “drugged drivers,” or those motorists who are illegally driving vehicles while under the influence of various drugs. In enforcing the DUI law, police seek to find “outward signs of impairment.”

After police stop a motorist who is under suspicion of driving under the influence due to a vehicle’s erratic operation, police have a conversation with the driver to ask whether he or she has been drinking or using drugs. If intoxication is suspected, police conduct a set of “standardized field sobriety tests.” Such tests include the officer asking the driver to walk and to turn and then to stand on one leg, Sgt Wood said.

Also, police ask the driver to have his/her eyes follow the movement of an object that police move laterally across the driver’s field of vision. An intoxicated person’s eyes typically exhibit a jerkiness as the eyes follow the moving object, the sergeant said.

Back at the police station, motorists suspected of driving under the influence of alcohol would be given a “breathalyzer” test in which they exhale air from their mouth into a tube to measure it for “blood alcohol concentration” (BAC).

A BAC of 0.08 percent or higher indicates the alcohol intoxication of a motorist for the purposes of the DUI law. In a stricter standard, a BAC of 0.04 percent or higher signifies alcohol intoxication for the driver of a commercial vehicle. In an even stricter standard, a BAC of 0.02 percent or higher indicates alcohol intoxication of a person under age 21.

However, the state has no definitive chemical test for marijuana DUI intoxication, Sgt Wood said. Besides the field sobriety tests, police obtain a urine sample from people suspected of marijuana intoxication for its chemical analysis, he said.

Police have been enforcing the state’s DUI law for many years, Sgt Wood noted. The potential for a more widespread use of marijuana as it is legalized more widely may result in police encountering more marijuana-based DUI situations.

“It’s just more of the same,” Sgt Wood said. “We’re looking at the potential for a greater volume of [marijuana]-impaired drivers,” he added.

In the course of their DUI enforcement, police may encounter people who have state approval to use medical marijuana who are intoxicated on such marijuana while driving, Sgt Wood said. Additionally, there are cases involving motorists intoxicated on various illicit drugs or intoxicated due to an overdose of legitimately prescribed drugs.

Based on his training as a drug recognition expert, Sgt Wood uses techniques designed to determine which of seven classes of drugs may be affecting intoxicated drivers. Those drug classes are: central nervous system depressants, inhalants, dissociative anesthetics, cannabis, central nervous system stimulants, hallucinogens, and narcotic analgesics.

In ceremonies late last year, Sgt Wood received the police department’s Law Enforcement Excellence Award. He joined the police department in 2004, becoming a sergeant in 2014.