Whether the United States will launch an attack on Iran’s nuclear facilities remains an open question — at the very least until after the November election. There are recent press reports that the arrival of three new US flotillas in Middle Eastern waters represents an unprecedented build-up since the crisis over Iran’s potential nuclear programme began.

At the same time, a report of the International Atomic Energy Authority of May 26 (pursuant to the Security Council’s fourth Iran sanctions resolution [1803, March 3, 2008]) sounds a worrying note. It expresses “serious concern” about some of Iran’s activities and notes that “contrary to the decisions of the Security Council, Iran has not suspended its enrichment-related activities”.

What is striking about the four wide-reaching Security Council sanctions resolutions is that the council - apparently learning from the broken US and UK ambassadorial assurances on the adoption of resolution 1441 regarding Iraq that there were no “hidden triggers” in it - have consistently stated in each resolution, in the clearest possible terms, that “further decisions will be required should . . . additional methods be required”. Given this formula, and that military strikes on Iran’s nuclear facilities would have massive adverse repercussions for peace and stability in the Middle East, it is safe to assume that in present circumstances the Security Council would not countenance an authorisation of the use of force against Iran.

So what are the legal issues for the UK if it were to repeat its practice in the Iraq invasion of allowing its bases to be used by the US? Crisis Action and Peacerights have recently commissioned an opinion on this from Rabinder Singh, QC, of Matrix Chambers, and Professor Vaughan Lowe, QC. Professor of International Law at Oxford University.

First, it addresses international law generally on the use of force. Leaving aside humanitarian intervention, there are two bases: self-defence under Article 51 of the UN Charter and where there is a Chapter VII authorisation from the council.

In the present circumstances only self-defence is a possibility. After noting that “no attack could be launched lawfully against Iran unless an attack by Iran were reasonably believed to be imminent” the opinion’s authors conclude: “It is in our view clear that any such attack upon Iran would amount to the crime of aggression as a matter of international law.”

The opinion then explores issues of state responsibility in international law in this context. The possibility of the British territory of Diego Garcia being implicated makes this opinion particularly important. Principles of state responsibility were codified by the UN’s International Law Commission in The Articles on Responsibility of States for Internationally Wrongful Acts (2001). Article 16 affirms that a state is internationally responsible for aiding or assisting a wrongful act by another state if: “a) that state does so with knowledge of the circumstances of the international wrongful act; and b) the act would be internationally wrongful if committed by that state”.

For the UK to incur responsibility under this rule several conditions must be met. First, it must be shown that active aid or assistance was given that materially facilitates or contributes significantly to the wrongful act. The authors state that “allowing US naval vessels to refuel or take on supplies at UK naval bases while they were on their way to participate in the attack” would entail UK responsibility.

Secondly, there must be knowledge of the circumstances of the wrongful act. It must be shown that the assistance was given “with a view to facilitating the commission” of the unlawful act and that it actually did facilitate it. Thirdly, the act that constitutes the unlawful conduct must be such that it would have been wrongful if it had been committed by the assisting state itself. The authors’ view is that this condition “would certainly be met”. Finally, the authors state their view that it is “absolutely inconceivable that UK bases could be used by US bombers to launch attacks on Iran without UK knowledge or at the least the UK’s acquiescence”.

Having concluded that if UK permission were granted for the use of facilities in these circumstances “that would undoubtedly entail the international responsibility of the UK . . . under international law” the authors proceed to analyse whether, under present English case law, the issue would be justiciable before domestic courts.

Their starting point is that a “concept of ‘non-justiciability’ has no place in modern public law” and that there should be no forbidden areas in relation to foreign relations and defence. This is because a fundamental principle of the English Constitution is the rule of law, and one aspect of this is that the executive does not have unlimited powers: that whether the executive has transgressed its legal powers is a question of law for the courts to decide.

Thus, if no error of law can be shown in these areas of foreign relations and defence the case will fail, not because is it is non-justicable, but because there is no legal basis for the court’s intervention. Further, in this context, the prohibition on the use of force is a peremptory norm of customary international law (jus cogens) and admits of no derogation. Thus, this rule is a source of English common law and the issues of international law discussed above are triable in domestic courts. Accordingly, at least declaratory relief might be granted with a court pronouncing its own views on the questions of international law at stake.

The author is the solicitor at Public Interest Lawyers. PIL was instructed by Crisis Action and Peacerights to obtain counsel's opinon on the UK's (legal) position if there was a UK strike on Iraq

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