UK-Mauritius Agreement on the Chagos Archipelago

Debate between Lord Wolfson of Tredegar and Lord Purvis of Tweed

Monday 30th June 2025 Lords Chamber

[Lord Wolfson of Tredegar (Con)]

My Lords, it is a pleasure to follow the noble Lord, Lord Kerr of Kinlochard, although he will appreciate that I take a very different position in responding to this interesting and important debate.

Before I turn to the more controversial points, let me start with a point on which there is unanimity. I welcome my noble and learned friend Lady Prentis of Banbury, who gave a truly magnificent maiden speech. As an Attorney-General, she was respected across the whole of the other place, and I am sure that her contributions here will be similarly listened to with great care across the whole of your Lordships’ House.

In my tradition, when we finish the annual reading of the Pentateuch with the end of Deuteronomy, we immediately start again with the first chapter of Genesis. In that spirit of linking a beginning and an ending, I also take this opportunity to mark the valedictory speech of her father, the noble Lord, Lord Boswell of Aynho. I am sure that, as the noble Lord leaves this House, it must be an especial pleasure to see his noble kinswoman—as I believe she is known—make the first of what I hope will be many contributions to our work.

This debate is required by statute before a treaty is ratified. Normally, with a treaty under the Constitutional Reform and Governance Act, we just have a debate. This is a different case. A treaty that cedes British sovereign territory to a foreign power cannot be ratified without an Act of Parliament. Professor Richard Ekins, in a Policy Exchange paper, has set out how every concession of British territory since 1890 has been enabled by primary legislation, the most recent example being the surrender of Hong Kong to China. In addition, since 1945, whenever a colony has achieved independence, either within or without the Commonwealth, primary legislation has been passed to renounce UK sovereignty under those territories. Indeed, FA Mann, a leading authority on foreign relations and the legally applicable principles, regarded this not just as a constitutional convention but as a legal principle.

In the Explanatory Memorandum, the Government appear to confirm that this is the position. Can the Minister inform us when this primary legislation will be brought before Parliament? Can we have a clear assurance that the treaty will not be ratified unless and until that legislation has received Royal Assent?

That is a problem with the Motion in the name of the noble Lord, Lord Purvis of Tweed, and why, in preference, I will support my noble friend Lord Callanan’s Motion. The former Motion states that the Government should not ratify the treaty until various matters have taken place, but the noble Lord has not included passing an Act to permit the cessation of British territory. I do not know whether it is now Liberal Democrat policy that a Government can give away sovereign territory without an Act of Parliament. It is a little odd. Those Benches are always so keen for Parliament to have a say before we even act in our own self-defence or support militarily our allies, but, apparently, they are keen now for Parliament to have no say before we cede sovereign territory.

In that respect, I regret the terms of Article 1 of the treaty, which states:

“Mauritius is sovereign over the Chagos Archipelago in its entirety, including Diego Garcia”.


That purports to accept that Mauritius is already the sovereign power. That is not the case in international law, as the UK has said repeatedly and consistently until this Government took office. It is also not the case in domestic law. Schedule 6 to the British Nationality Act 1981 includes the British Indian Ocean Territory as one of the British Overseas Territories—and that is also reflected elsewhere in the Act. All of that can be amended only by domestic legislation and an Act of Parliament. If the Act is not passed and the treaty is therefore not ratified, the effect in international law of the Government even agreeing a treaty in these terms will be to weaken our legal position over the Chagos Islands, even before the Bill has been laid before Parliament, which is to be regretted.

Why are we here at all? We are here because Mauritius has claimed sovereignty since 1981, despite decades of Mauritian Governments saying that they did not make any such claim. As we have heard, an ICJ advisory opinion in 2019 opined against the UK’s administration of the islands. The noble Lord, Lord Hannay of Chiswick, referred to that as a “ruling” in a rare, but perhaps Freudian, slip. I suggest that it is not a ruling at all; it did not, in terms, talk about the sovereignty of the islands at all. An advisory opinion is not a ruling, a judgment or a binding decision of any sort. The clue is in the name: it is an advisory opinion.

The United Kingdom would have to agree for the International Court of Justice to deliver a binding opinion or judgment. We would have to agree to submit the question of jurisdiction to the ICJ. We have not. I would hope that, even under this Government, we would not. Without that, there would be no binding ruling from the ICJ. While I recognise the political force of advisory opinions, we need to be clear-eyed about them: they are not binding.

We as a country have never accepted that we would always act in accordance with advisory opinions. Indeed, in 1996, an advisory opinion came within one vote of holding that the use of nuclear weapons would nearly always be illegal. Would we, if that vote had gone the other way, have unilaterally disarmed ourselves of all or most of our nuclear arsenal? Perhaps we would have done if this Government, with this Attorney-General advising them, were in charge; I just do not know.

The Government appear to accept that the advisory opinion is not binding, but they say, “Oh, ITLOS—the International Tribunal of the Law of the Sea—may assume that the advisory opinion is binding and that Mauritius is sovereign and exercise its own jurisdiction on that false premise”. But there are two problems with that: ITLOS has no jurisdiction to adjudicate a territorial dispute, nor can it properly take it that the question of sovereignty has been decided by an advisory opinion.

To respond to a point from the noble Lord, Lord McDonald of Salford, the advisory opinion is not binding—to use the noble Lord’s words—on ITLOS. An advisory opinion, as is made clear on the website of the ICJ itself, is not even binding on the particular agency which has asked for the advisory opinion, so it is certainly not binding on ITLOS. Secondly and relatedly, the United Kingdom should not accept that its sovereign rights can be taken away from it by one tribunal, ITLOS, misreading and misunderstanding the advisory opinion from the ICJ.

To pick up the point made by the noble Lord, Lord Kerr, ITLOS has no jurisdiction in relation to this dispute and we should not accept any ruling that takes for granted that the ICJ has established authoritatively that Mauritius is sovereign, first, because it has not and, secondly, because we would not give our consent to any such judicial determination. We should not, I suggest, give up our sovereign territory because of a fear that ITLOS might wrongly issue some order for some vague protective or provisional measures against us at some future, indeterminate date.

Of course I recognise that an advisory opinion gives the risk that future legal proceedings could be brought against us, but it is a terrible precedent, I suggest, for us to give up territory because we are worried that an international tribunal might in the future reach a conclusion which we regard as legally flawed. I have to say that, if British foreign policy is henceforth to be at the mercy of the vote of the United Nations General Assembly, then it really is game over.

The noble and learned Lord, Lord Goldsmith, referred to the—excellent, if I may say so—report from his committee, which I enjoyed reading. In that report, there is a reference to the fact that if we were to stand in the face of an advisory opinion by the ICJ, we would somehow be in the same position as Russia is in relation to the invasion of Ukraine. I hasten to add that that is not the view of the committee, but it was the view ascribed in its report to evidence it took from Professor Sands. The notion that standing on our legal rights in the face of a non-binding advisory opinion makes us like Russia invading Ukraine is less a piece of considered legal analysis and more a piece of advocacy. My late father used to say about one partisan newspaper that it was difficult to see where the news ended and the comment began. When reading Professor Sands’ evidence to the committee, it was very difficult to see where the analysis ended and the advocacy began.

[Lord Purvis of Tweed (LD)]

I am listening attentively to what the noble Lord is saying. If he has time, could he outline a little more of the background to the decision James Cleverly made in November 2022 to open negotiations on the exercise of sovereignty?

[Lord Wolfson of Tredegar (Con)]

I am going to deal with the legal issues affecting this because the Government are saying to us, “We have no choice: we have to sign this because we have legal risk”. There is no point the noble Lord muttering from a sedentary position.