Mark McCloskey is an associate in the firm’s International Dispute Resolution Group, resident in the London office.

Mr. McCloskey’s practice includes contentious and advisory work on a range of complex international law issues, including in international investment and commercial arbitration, human rights, public international law and commercial litigation.  He has advised clients in various industries, including energy and natural resources, infrastructure and financial services, under the ICC, ICSID, LCIA and UNCITRAL rules, and before domestic courts.  

He has experience of parallel extradition and criminal investigations in the civil courts, and was part of a team that successfully obtained provisional measures from an ICSID tribunal to suspend extradition proceedings in relation to one of the investor’s officers. He also advises investment firms and asset managers in evaluating investments in international claims or arbitration awards.

Mr. McCloskey’s representations in the Courts of England & Wales include disputes raising complex issues of private international law and corporate social responsibility. He has acted on cases at all levels of the court system, including before the UK Supreme Court.

Mr. McCloskey has an active pro bono practice, focused on public international law issues, including human rights claims brought before UN human rights treaty bodies, domestic courts and other international human rights bodies. His representations in this space include a successful intervention before the UK Supreme Court concerning Northern Ireland’s abortion laws and multiple complaints to the UN Human Rights Committee concerning sexual and reproductive violence. He has also received an International Bar Association Group Member Award in recognition of his involvement in the roster of lawyers supporting the IBA’s eyeWitness project, an initiative which harnesses the power of technology to help bring to justice those enabling and encouraging unspeakable cruelty.

Mr. McCloskey has a particular interest in European law issues arising in the investment dispute space, and since 2019 has been an editor of the European Investment Law and Arbitration Review, co-published by the European Federation for Investment Law and Arbitration and Queen Mary University of London. He sits on the Executive Committee of the London Irish Lawyers Association, and is actively involved in the public international law and arbitration communities (including the YIAG, YPILG, Young ITA, Young ICCA and Arbitration Ireland).  He has previously been invited to speak on international arbitration at Kings College London. 

Mr. McCloskey joined Debevoise as a trainee solicitor in 2014 and was admitted as a Solicitor of the Senior Courts of England & Wales in 2016.  He graduated from the University of Manchester in 2011 with an LL.B. (Hons) and the University of Law in Guildford in 2013 where he completed his LPC (distinction).  He speaks and handles matters in Spanish.


  • University of Law, L.P.C.
  • University of Manchester, LL.B.

Bar Admissions

  • Solicitor, England & Wales