Reduction in Late-Night Violence following the introduction of National New Zealand Trading Hour Restrictions

BACKGROUND: This study aimed to assess the early impact of national alcohol trading hour restrictions on nighttime violence in New Zealand. The new national maximum trading hour restrictions prohibited 24-hour trading by reducing hours to between 8 am and 4 am for on-premises and between 7 am and 11 pm for take-away outlets. METHODS: A telephone survey of alcohol outlets was undertaken to determine actual trading hours before the law change. Interrupted time-series analysis modeled weekly nighttime police calls for service for assault (i.e., between 9 pm and 6 am) and late-night police calls for service for assault (i.e., between 4 am and 6 am) from 2005 to 2015. Daytime police calls for service for assaults were used as the comparison group. Abrupt permanent changes and gradual permanent changes were assessed. RESULTS: The survey found that only 1% of alcohol shops, 9% of supermarkets, and 6% of bars/nightclubs were affected by the hour restrictions because they did not trade as long as their licensed hours permitted in the first place. The time-series analysis found no effect of the national trading hour restrictions on nighttime police calls for service for assaults. However, a significant gradual permanent decrease of 12.4% was found for late-night assaults between 4 am and 6 am (i.e., those likely related to the on-premises hour restriction). This equated to a weekly average decrease of 4.3 police calls for service for assaults between 4 am and 6 am following the law change. CONCLUSIONS: The national trading hour restrictions for on-premises and take-away outlets affected only a small proportion of premises, and no change in the overall level of nighttime violence was found following the restrictions. Late-night assaults likely related to on-premises, however, did reduce showing the likely effectiveness of trading hour restrictions even when the impact of the law change on the ground was minimal.