Background. We summarize the facts the judge could have found, viewing the evidence in the light most favorable to the Commonwealth. See Commonwealth v. Latimore, 378 Mass. 671, 676-677 (1979). On August 18, 2015, Joseph Ruggerio heard a crash and observed a vehicle on its side on his front lawn. The defendant, the sole occupant of the vehicle, was in the driver's seat and appeared to be unconscious. Detective David Mahoney arrived at the scene. He knew the defendant prior to the crash and attempted to rouse her by pounding on the vehicle and screaming her name, but she did not respond. Paramedics Jonathan Martel and Alexander Schlageter arrived and secured entry into the vehicle. When Martel touched the defendant's shoulder and called her name, the defendant opened her eyes and communicated with him "slightly," but she appeared drowsy and was "kind of incoherent when speaking." Mahoney, Martel, and Schlageter observed a bluish substance on the defendant's mouth and tongue. In the ambulance, the defendant became more alert. The paramedics asked the defendant where she had been that night and whether she had taken any alcohol or drugs, to which she responded, "her Clonopins [sic ]."1 At the hospital, the defendant was diagnosed with postconcussion syndrome. There were no toxicology tests conducted on the defendant.