A tale of two cities: the effect of extended drinking hours in licensed establishments on impaired driving and assault charges.

Objectives: On May 1, 1996, Ontario, Canada, amended the Liquor Licence Act to extend the hours of alcohol sales and service in licensed establishments from 1 to 2 a.m. The purpose of this study was to examine the effect of extended drinking hours on two cities in southwestern Ontario, Canada, one of which (London) would be affected by the alcohol control policy of extended drinking hours and the second city (Windsor) would be affected by two alcohol policies, extended drinking hours, and cross-border legal drinking age differences between Ontario and Michigan. Specifically, this study tested whether there were differences in impaired driving and assault charges in London and Windsor, Ontario, concomitant with the extended drinking hour amendment.

Methods: A quasi-experimental design using interrupted time series was used to assess changes. The analyzed data sets were monthly police impaired driving and assault charges data for Ontario, for the 11-12 p.m., 12-1 a.m., 1-2 a.m., 2-3 a.m. and 3-4 a.m. time windows, for 4 years pre- and 3 years post-policy change.

Results: Overall, London and Windsor exhibited significant overall reductions in impaired driving charges and no changes for assault charges aggregated over the 11 p.m.-4 a.m. time period after the drinking hours were extended. Within the different time windows, London showed significant decreases for the 1-2 a.m. Sunday-Wednesday and Thursday-Sunday time periods and a significant increase for the Sunday-Wednesday 3-4 a.m. time period, while Windsor demonstrated significant decreases in impaired driving charges for 1-2 a.m. Sunday-Wednesday and Thursday-Saturday time periods and significant increases for Sunday-Wednesday 2-3 and 3-4 a.m. and for Thursday-Saturday 2-3 a.m. For assault charges, no overall pre-post differences were found for the aggregated 11 p.m.-4 a.m. time period for either city. When the data were disaggregated by hour, a significant decrease was found in London for Thursday-Saturday 1-2 a.m. and significant increases for Sunday-Wednesday 2-3 a.m. and Thursday-Saturday 3-4 a.m. time periods, while no significant decreases were found in Windsor during the 1-2 a.m. time periods and one significant increase occurred during the Thursday-Saturday 2-3 a.m. time period.

Conclusions: These findings, based on police data, suggest no overall effect on charges aggregated over the 11 p.m. to 4 a.m. time window, although some differences were observed for the different hours after 2 a.m., with a possible effect of the one hour extension of drinking in licensed establishments.