Increase in cannabis‐related emergency department presentations in the period immediately before legalization requires explanation.

The article discusses a study by D. T. Myran and colleagues which reported on changes in cannabis related emergency department (ED) attendances in Ontario across a period of major policy change in Canada. Topics include the time periods that were included in the study, factors that may explain the rapidly increasing rate of ED attendances in the two years before legalization, and the most important oversight by the authors regarding the pre-legalization phase.