Police officers sat in a Danvers classroom and watched a scene from a Cheech and Chong movie. It was the introduction to a two-day training class that’s become more popular since marijuana became legal in Massachusetts. Advanced Roadside Impaired Driving Enforcement is referred to as ARIDE. It builds on the training all police go through in the academy, and it’s the first step to eventually get certified in drug recognition.

“Eyes only. Don’t move your head,” said an instructor, demonstrating the same roadside test used to determine drunk driving, but with additional symptoms for officers to look for, which could signal if a driver is high on marijuana or other drugs.

“At least once or twice a shift, if you have an officer out doing proactive traffic enforcement, they’re going to run into somebody that’s been doing marijuana in the car,” said Lt. Stephen May, an instructor who teaches officers the telltale signs. “Marijuana, cannabis, whether they’re smoking, vaping, edibles, generally it dilates the pupils.”