The Supreme Court has held that the Administrative Court was wrong to exclude a Wikileaks cable from evidence. The underlying judicial review proceedings in R (Bancoult No.3) v Secretary of State for Foreign and Commonwealth Affairs [2018] UK SC 3 concerned a challenge by the Chagos Refugees Group (CRG) to the British Government’s decision to establish a marine protected area around the Chagos islands, preventing Chagossians from continuing their commercial fishing businesses in the region. However, the issues raised are of wider application.

At the heart of the case was a leaked cable from the US Embassy in London to the US State Department in Washington summarising a conversation between British and US officials regarding the reasons for establishing the protected area. The Foreign and Commonwealth Office (FCO) argued that the cable formed part of the US Embassy’s diplomatic archive, which was protected by the 1961 Vienna Convention, and was therefore inadmissible.

The Supreme Court stated that there were two qualifications to the principle of diplomatic inviolability:

  • The document must remain part of the mission archive.
  • It must not have been so widely disseminated in the public domain as to lose any character of confidentiality.

The Supreme Court unanimously held that the cable did not meet these conditions. It had most probably been obtained (albeit unlawfully) from the State Department archive rather than directly from the US Embassy. It was therefore no longer part of the mission archive at the point when it was obtained. Further, the publication of the cable by Wikileaks and the newspapers had put it into the public domain in circumstances for which CRG had no responsibility.


While the Supreme Court stressed that the decision was made on the specific facts of this case, in principle it seems likely that the same considerations will apply to many of the documents published by Wikileaks, in particular those which record diplomatic communications from an embassy to its government and which have been widely disseminated in the media. Since such communications will naturally tend to focus on policy matters, this decision will be of particular interest to those involved in judicial review proceedings. Parties involved in judicial review should remember to consider such material as a possible source of evidence at an early stage, to allow time for relevant searches to be carried out.