Case details

R (on the application of Bancoult No 3) (Appellant) v Secretary of State for Foreign and Commonwealth Affairs (Respondent)

Case ID: UKSC 2015/0022

Case summary


  1. Whether the Court of Appeal should have held that evidence wrongly held to be inadmissible by the court below (the "Wikileaks cable") could and would have led to the conclusion that the decision of the respondent to create a marine protected area in the British Indian Ocean Territory (BIOT) was motivated by an improper purpose;
  2. whether the Court of Appeal erred in finding that the Secretary of State was not personally motivated by the alleged improper purpose and relying on that fact to conclude that the decision of the court below on admissibility would have made no difference;
  3. whether the Court of Appeal erred as to a fundamental fact going to the lawfulness of the consultation that the Government of Mauritius had not asserted a right to fish in BIOT based on undertakings given by the United Kingdom and separate from its claims to sovereignty*; and
  4. (in an argument raised by the respondent) whether the Court of Appeal erred in ruling that the Wikileaks cable was admissible in evidence. The Court must also determine whether the appellant has permission to adduce new evidence that was not available to the courts below in support of its grounds.

* The Court has not yet granted permission to appeal on this ground but will hear submissions at the hearing.


The appellant is Chair of the Chagos Refugees Group, a group which represents the former inhabitants of the Chagos Archipelago (BIOT) who were removed between 1968 and 1973 and prevented from returning by the United Kingdom Government. In these proceedings the appellant challenged the decision of the respondent Secretary of State to establish a ‘no take’ marine protected area (MPA) in April 2010 in the BIOT, which brought to an end all commercial fishing including that carried on by Chagossians as owners and crew of Mauritian registered fishing vessels. In relation to the issues that are before the Supreme Court, the appellant alleges that the respondent’s decision was motivated by the improper purpose of preventing future resettlement of the islands, and that the consultation which preceded it was flawed by non-disclosure of the fact that the decision would interfere with Mauritian (and therefore Chagossian) fishing rights in BIOT. In the courts below, the evidence relied on to establish the improper purpose was primarily a US diplomatic ‘cable’ put into the public domain by Wikileaks. The appellant also now seeks to adduce further evidence that was not made available to the courts below from:

  1. Foreign Office files released to the National Archives following the Court of Appeal's decision; and
  2. evidence from the arbitration between the United Kingdom and Mauritius pursuant to Article 287 and Annex VII, Article 1 of the United Nations Convention on the Law of the Sea that has been made publicly available.
Judgment appealed

[2014] EWCA Civ 708



Louis Olivier Bancoult


Secretary of State for Foreign and Commonwealth Affairs



Lord Neuberger, Lady Hale, Lord Mance, Lord Kerr, Lord Clarke, Lord Sumption, Lord Reed

Hearing start date

28 Jun 2017

Hearing finish date

29 Jun 2017

Watch hearing
28 Jun 2017 Morning session Afternoon session
29 Jun 2017 Morning session Afternoon session