Objective: To compare opioid prescribing behavior of emergency medicine providers following the enactment of Connecticut Public Act (PA) 15-198 at a large academic tertiary medical center. Methods: This study is a single-center pre and postlaw retrospective cohort of ED patients discharged with opioid prescriptions. Patients discharged from January 1, 2015, to June 30, 2015, were analyzed as the prelaw cohort, and patients discharged from January 1, 2016, to June 30, 2016, were analyzed as the postlaw cohort. The primary outcome was the cumulative dose of solid dosage forms of opioids per prescription, calculated in morphine milligram equivalents (MME). Results: A total of 10,307 prescriptions included in the final analysis. A statistically significant decrease in the primary outcome was seen in the postlaw cohort compared with the prelaw cohort, respectively (75 MME [interquartile range, IQR: 60-100) vs 80 MME [IQR: 75-150]; P < .001). The postlaw cohort also saw 1289 (22.2%) fewer opioid prescriptions, primarily driven by a reduction in the number of schedule II opioids prescribed. In a posthoc analysis, the primary outcome remained statistically significant even when opioid prescriptions were only included if their prebuilt settings were unchanged between pre and postlaw cohorts, respectively (85.1%; 95.6 MME (±56.0); n = 5041 vs 86.7 MME (±39.6); n = 3713; P < .001). Conclusions: The passage of PA 15-198 was associated with a decrease in the cumulative dose of opioids per prescription of solid dosage form products. This drop was precipitated by a transition from using opioids in schedule II to opioids in schedule IV and a modest decrease in prescribed opioid quantity.