UK-Mauritius Agreement on the Chagos Archipelago

Debate between Lord Wolfson of Tredegar and Lord Hannay of Chiswick

Monday 30th June 2025 Lords Chamber

[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.

[Lord Hannay of Chiswick (CB)]

My Lords—

[Lord Wolfson of Tredegar (Con)]

I will finish the point and give way. This Government are trying to dress up a political decision as a legal decision. Now, of course, I am happy to give way.

[Lord Hannay of Chiswick (CB)]

I just wanted to ask the noble Lord to address the testimony given to the committee by Sir Christopher Greenwood, rather than having a lot of fun at the expense of Mr Philippe Sands.

[Lord Wolfson of Tredegar (Con)]

I have. Sir Christopher Greenwood made the point that we have legal risk. He is absolutely right: there is legal risk. But I am suggesting that we need to analyse that legal risk carefully.

There has been very little reference in the debate so far to the other evidence taken by the committee from Professor Ekins. Indeed, it is a shame that we have not been able to hear from the noble Lord, Professor Lord Verdirame, this afternoon because I would be very interested to hear his view on this issue. Ultimately, the committee heard from three lawyers. There is a difference of legal opinion on this issue, and that is because, ultimately, this is a political and not a legal decision.

Let me turn now to Article 4 of the treaty, which has not yet been raised. The premise of the agreement rests on the proposition that our interests will align with those of Mauritius for the next 99 years to the extent that there is no appreciable risk that Mauritius—and it has, of course, retained lawyers of the highest calibre—will seek to leverage the terms of the treaty for its own benefit. Merely to state that assumption is to show how unsafe it is.

I say 99 years; I was very surprised that the noble Lord, Lord McDonald, referred to 140 years. The ability in the treaty to extend it for 40 years is really not worth the paper it is not written on. There is simply no legal right to extend. There is an ability to negotiate, and the idea that there will be an extension, absent perhaps another huge payment of money, really is for the birds.

Article 4 provides:

“Each Party agrees to ensure that in the implementation and application of this Agreement, including activities in relation to the Base, there shall be compliance with international law”.


No court or body is appointed to deal with that issue. If Mauritius, advised by its eminent lawyers, took the view that UK or US operations out of Diego Garcia are not in accordance with international law, then it could allege the UK was in breach. That would not entitle Mauritius to terminate the treaty—the rights of termination are limited in Article 15—but it would entitle it to take countermeasures which would otherwise be prohibited under the treaty, such as allowing the presence of armed forces of other countries or constructing installations elsewhere on the islands that might adversely affect the security of Diego Gracia. Let us be clear: if Mauritius took that action, there would be nothing that we could do and we would not be entitled to stop paying the sums that we have promised to pay under the treaty.

There is a similar legal risk under Annexe 1. It was mentioned earlier that we have to inform Mauritius about the use of force originating from the base at Diego Garcia “expeditiously”. I have three questions for the Minister in this regard. First, my understanding is that the UK’s position is that this provision requires notice only after an operation is launched. Is that correct? Secondly, assuming that it is only after an operation is launched, what do we consider “expeditiously” means? Does it mean that we have to inform Mauritius as soon as the planes take off, or can we deliberately decide to delay informing it, even though we could inform it, until the operation has been completed? Thirdly, whatever our interpretation of that word might be, have we agreed that interpretation with Mauritius? If we have not, I can give the Minister some free legal advice: all of this is very ripe for a further dispute, which would likely result in Mauritius not abiding by its obligations under the treaty.