A “phenomenon of our time”: When are intelligence leaks admissible in Court?



The decision of the Supreme Court in R (on the application of Bancoult No 3) (Appellant) v Secretary of State for Foreign and Commonwealth Affairs (Respondent) [2018] UKSC 3, published on 8 February 2018, provides an overview of when the court will admit leaked intelligence material as evidence.


Chagossians are currently prohibited from returning to the Chagos Islands under the Constitution and Immigration Orders 2004 of British Indian Overseas Territory of the Chagos Islands; a matter that has been the subject of a number public law and human rights cases for more than a decade. In this case, the Chair of the Chagos Refugees Group challenged the decision of the Secretary of State to establish a Marine Protected Area (“MPA”) in the BIOT, in which there would be no fishing.

The details of a meeting between British civil servants and US diplomats was set out in a cable sent to the US Government, elements of the US military and the US Embassy in Mauritius from the US Embassy in London. It was later shared by WikiLeaks with The Guardian and The Telegraph which both published it.

The Chagos Refugee Group considered that the document said to be a leaked cable suggested that the British Government’s decision to proclaim the MPA in BIOT was motivated by an improper ulterior motive: to make any future resettlement by the Chagossians impracticable. The Claimant brought a challenge by way of judicial review against the Secretary of State, on the basis that the MPA was unlawful as a result (among other reasons).

The issue

Key to this question was whether the ’inviolable’ status of official correspondence from diplomatic missions afforded by the Vienna Convention on Diplomatic Relations (the “Convention”) meant that it was not admissible as evidence.

Through a series of appeals, the matter came before the Supreme Court.


The Supreme Court held that the cable was, in fact, admissible as evidence before the Court.

The Court determined that, on the balance of probability, the document was unlikely to have remained part of the archives of the London mission or to have been leaked from there.

It was further held that the document’s “inviolable” status could potentially be lost due to a document from the mission archive coming into the public domain, albeit that each case would need to be determined on its facts following, by analogy, the reasoning around the law of confidentiality.

It was also said that, in principle, the Convention protects documents under the control of a mission but not documents which never were or are no longer under its control.

While English courts cannot, consistently with the privileges and immunities of a diplomatic mission, be the means by which a document comes into the public domain, if the documents have been published, their confidentiality has already been destroyed and there is nothing left to be preserved in connection with the Convention. Therefore documents which are already in the public domain will be afforded no greater protection simply as a result of having originally emanated from a diplomatic mission.

The Court left it open for subsequent courts to consider factual scenarios in which this rule may need to be refined, for example if the person that put the information in the public domain is the party seeking to rely on its contents.

However, the majority of judges held that, in this case, they did not consider that the cable would have assisted the Claimant’s case, even if it had been admitted in the initial hearing of the judicial review. They found, in essence, that:

  • The evidence did not support a finding that the civil servants had an improper motive;
  • Even if they had, on this occasion the Secretary of State was briefed and then took the decision himself and there was no evidence of improper motivation on his part.

Their Lordships noted that there may be circumstances where an improper motive on the part of a Minister’s civil servants may taint the lawfulness of his/her decision, such as if a Minister simply relies on a civil servant in effect to take a decision in the Minister’s name, if there was a collective decision making process or the decision was taken in ignorance or on the basis of incorrect or incomplete information compiled by civil servants.

The appeal was also not allowed on any of the other bases raised by the Claimant.


Lord Sumption referred to the availability of leaked State information as “a phenomenon of our time”. The Supreme Court has determined that the fruits of such leaks will not be protected (in particular) by the Convention and commented more broadly, that once in the public domain, previously protected material may be relied upon in challenging the Government by judicial review.  

If you would like to discuss any of the issues raised in this case, please contact Emma Dowden-Teale. 


This information is necessarily of a general nature and doesn’t constitute legal advice. This is not a substitute for formal legal advice, given in the context of full information under an engagement with Bates Wells.

All content on this page is correct as of February 9, 2018.