After leaving the EU the role of policing and ensuring fair competition in UK markets (including state aid) will fully transfer to British regulators and agencies. This could result in differences to the current approach – for instance on approvals for mergers and acquisitions.
Resources and information
The Competition and Markets Authority (CMA) has published a notice on its role after Brexit http://www.gov.uk/government/collections/cmas-role-after-brexit
If there is no Brexit withdrawal agreement before March 2019, the government has developed a ‘no deal’ competition Statutory Instrument (SI):
Mergers: if the European Commission has issued a decision on or before 29 March 2019 (unless the decision is annulled, in full or in part, following an appeal), the UK has no jurisdiction.
State aid: the government is expected to pass secondary legislation which will transpose EU state aid rules into UK law and provide for the CMA to take on its new state aid role, following which they will publish further details on how this function will operate.
Antitrust: After the UK’s exit from the EU, the CMA will no longer have jurisdiction to apply anti-competitive agreements including cartels or on abuse of dominance.