Baroness Chapman of Darlington (Lab)

I am speaking for myself; other noble Lords may take different views on that point. Mauritius could also pursue a legally binding judgment through further arbitral proceedings against the UK under Annex VII of the UN Convention on the Law of the Sea, or UNCLOS. A judgment from such a tribunal would be legally binding on the UK—and I will come on to the points about the extent of those judgments and sovereignty, too. Such cases could be brought rapidly and include provisional measures, themselves legally binding, which could be introduced within weeks. The long-standing legal view of the United Kingdom is that the UK would not have a realistic prospect of successfully defending its legal position on sovereignty in such litigation. The other important element to note here is that, even if the UK chose to disregard any legal rulings—that is not something that this Government would want to do, but we could—we rely on third countries to service the base. Therefore, the operability of the base depends on other states taking a view on such rulings. We of course control what we do, but we cannot control what other states do. If we need those states to agree with us and to ignore a legal ruling too, we may not be successful. It may be that we then compromise the operability of the base. That is a very real threat; we were concerned about that, as were our allies and partners, including the United States. The risk of a binding ruling relating to sovereignty from this type of tribunal is simply too great, given the importance of the base for national security. Some have pointed to the 2015 arbitration between the UK and Mauritius, in which the tribunal was clear that it did not have jurisdiction over the question of sovereignty. That is right. However, that was before the advisory opinion in 2019 and before the 2021 judgment of a special chamber of the International Tribunal for the Law of the Sea in a case about delimitating the boundary between Mauritius and the Maldives. In that case, it was ruled that Mauritius’s sovereignty was inferred from the ICJ’s advisory determinations. These have changed the legal landscape.