In a bid to reduce alcohol-related violence, the New South Wales Government recently proposed introducing mandatory minimum prison terms for assault. This article addresses the question of whether the threat of mandatory minimum penalties would reduce the incidence of assault. We exploit an earlier sentencing reform in New South Wales (the introduction of standard non-parole periods) in which longer minimum periods in custody were announced but never actually carried into effect. We use time series structural modelling to see whether assault rates in New South Wales were affected by the threat of more severe penalties. No evidence is found that the threat of longer prison terms had any effect on the incidence of assault in New South Wales. The article discusses the policy implications of this finding and concludes that liquor licensing policy is a more cost-effective policy instrument for dealing with alcohol-related violence than sentencing policy.