Hugh Mercer QC has a wide-ranging practice in public law, judicial review and commercial law especially where cases involve specialist issues of conflict of laws, foreign law and EU law.  He has extensive experience in trial and appellate advocacy, especially in the UK Supreme Court, and is equally at home in arbitral tribunals.

He covers the entire field of EU, public and international law providing advocacy and representation not only before the Court of Justice and General Court but also before a wide range of courts and arbitral tribunals both in the UK and, working with local counsel, in Belgium, France, Greece, Spain and Switzerland where his languages (French, German, Spanish and Italian) are very valuable.

A member of Treasury A Panel when a junior, his work since taking silk has included several recent cases involving sanctions/restrictive measures before the General Court, national courts and regulatory authorities, including intervening in the General Court of the EU to support Microsoft's appeal against a periodic penalty payment of almost €1 billion and successfully appealing a Court of Appeal decision in the fisheries field to the UK Supreme Court on behalf of Defra.

He is Chairman of the CCBE EU Lawyers Committee, a committee which handles cross border regulatory issues affecting all EU Bars, and is on the Legal Experts Advisory Panel of Fair Trials International. He also co-authors a major commentary on the Brussels Regulation on jurisdiction and judgments, European Civil Practice. 

He has experience both as expert witness on English law and also as arbitrator, including as sole arbitrator.