Following the United Kingdom's decision to withdraw from the European Union, the legal framework governing jurisdiction, recognition and enforcement of judgments in parental responsibility disputes, and child abduction, is likely to be significantly altered. This paper examines the approach adopted by European family law to the resolution of disputes over children. The concept of ‘mutual trust' is identified as underpinning cooperation between EU Member States in international family disputes. It will be suggested that the loss of reciprocity between the UK and the remaining Member States of the Union means that adopting the Brussels IIa Regulation following ‘Brexit' is not a feasible legal framework. In examining the Hague Convention on the Protection of Children 1996 as a potential alternative to the current Brussels IIa Regulation to regulate cross-border disputes over children, it is argued that the impact of EU law in emphasising the importance of mutual trust between legal systems in family law may have a long-lasting impact on English family law into the future.