Protection orders are a common legal response to domestic violence which aim to prevent further re-victimisation by the perpetrator.The current study systematically reviews research into the use and impact of protection orders, using the EMMIE framework (Effectiveness, Mechanisms, Moderators, Implementation and Economy).Meta-analysis is used to examine the overall effect of protection orders, while narrative synthesis is used to examine the underlying mechanisms and moderators of their effectiveness, their implementation and economic viability.Protection orders are associated with a small but significant reduction in domestic violence. They appear to be more effective under certain circumstances, including when the victim has fewer ties to the perpetrator and a greater capacity for independence, and less effective for offenders with a history of crime, violence and mental health issues.