Although no changes will affect competition law and enforcement in the immediate future, the long-term implications of Brexit depend on the relationship between the United Kingdom and the European Union.

Competition law and enforcement in the United Kingdom will remain business as usual in the immediate future. Further out, much will depend on the shape of the arrangements that are struck in respect of the relationship between the United Kingdom and the European Union. For example, should the United Kingdom choose to join the European Economic Area (EEA) on withdrawal (the so-called “Norway option”), there would not be significant changes to the law itself (because the competition rules in the EEA Agreement are modelled on their EU equivalents), however, disputes about its interpretation in the EEA would ultimately be resolved by the EFTA Court rather than the EU Court of Justice. However, should the United Kingdom decide to “go it alone” and withdraw from the European Union completely, UK competition law alone would then apply. In that case, mergers that met the EU merger control thresholds would potentially need to be notified in the United Kingdom as well as to the European Commission in Brussels.

Furthermore, the UK Competition and Markets Authority could investigate abusive conduct or a cartel that was already the subject of a parallel European Commission investigation. Finally, it is unlikely that European Commission cartel infringement decisions would be binding in the United Kingdom and thus, actions for damages (including class actions) before the UK courts arising out of such decisions would involve questions of liability as well as quantum, necessitating extensive discovery and expert evidence.

Overall, therefore, the greater the loosening of the constitutional and institutional ties between the United Kingdom and the European Union as a result of Brexit, the more complex and duplicative the resulting competition law regime will likely be.