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

The case of R (on the application of Bancoult No 3) v Secretary of State for Foreign and Commonwealth Affairs was an appeal by the Chagossians, who were removed from the British Indian Ocean Territory (BIOT) in the early 1970s, against the decision of the Secretary of State to establish a Marine Protected Area (MPA) in the BIOT. The Chagossians argued that the creation of the MPA was motivated by an ulterior motive to prevent their resettlement in the BIOT and that the consultation process preceding the decision was flawed due to the failure to disclose the arguable existence of Mauritian inshore fishing rights. The Supreme Court was required to decide whether the court below had erred in its ruling that the exclusion of a purported cable from the United States Embassy in London from use before the Administrative Court would or could have made any difference to that Court's decision on the issue of improper purpose. The Supreme Court also needed to determine whether the cable had lost its inviolability due to its dissemination in the public domain.

The Supreme Court found that the cable was admissible as evidence as it had lost its inviolability due to its publication by Wikileaks and subsequent newspaper articles. The Court of Appeal's conclusion that the admission of the cable in evidence would have made no difference was rejected by the Supreme Court, which found that there was a substantial possibility that the Administrative Court would have taken a different view of the evidence if the cable had been admitted and that there was an equally substantial possibility that it would have concluded that the Foreign Secretary's decision could be impugned because it was taken on a misapprehension of the true facts and circumstances.

The Supreme Court allowed the appeal and ordered that the matter be remitted for hearing before a Divisional Court with the direction that it be reconsidered on the basis that the cable was admissible in evidence. The court emphasized that the purpose of the inviolability rule is to allow the mission to communicate in confidence with the sending government and that documents emanating from a mission must retain their confidentiality and consequent inviolability in some circumstances. However, in this case, the cable had lost its inviolability due to its dissemination in the public domain.