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Iran Conflict 2026
24MAR

UK attorney general: war unlawful

3 min read
05:37UTC

The UK attorney general advised that the US-Israeli campaign breaches international law. Starmer opened British bases for it anyway.

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Key takeaway

Unlike Iraq 2003, the UK government has acted against — not around — its chief legal officer's formal advice.

Lord Hermer KC, the UK attorney general, advised the government that the US-Israeli military campaign against Iran does not accord with international law 1. That assessment shaped Prime Minister Starmer's initial refusal on 28 February to grant Washington access to any British military facilities 2. Starmer reversed within 48 hours, authorising "specific and limited defensive operations" from RAF Fairford and Diego Garcia while refusing RAF Akrotiri in Cyprus for offensive strikes. A former Director of Public Prosecutions now facilitates operations his own chief law officer assessed as unlawful.

Chatham House published analysis arguing the distinction between defensive and offensive base use "blur[s] the line between lawful self-defence and unlawful war on Iran" 3. Under Article 16 of the International Law Commission's Articles on State Responsibility, a state that knowingly aids another's internationally wrongful act bears international responsibility — regardless of how it categorises its contribution. The label "defensive" does not insulate London if the underlying campaign is assessed as unlawful.

The UK faced a version of this in 2003. Attorney General Lord Goldsmith's advice on the Iraq invasion — initially equivocal, later firmed up under political pressure — consumed the Chilcot Inquiry for seven years and destroyed the Blair government's credibility on the use of force. Starmer's legal exposure is sharper: Goldsmith's advice was ambiguous; Hermer's, as reported by Middle East Eye, is not 4.

Iran had warned the UK on Thursday that permitting US access to British bases made Britain "a participant in aggression." Within hours of London confirming that access, two intermediate-range ballistic missiles were fired at Diego Garcia — the first Iranian weapons aimed at British sovereign territory in this conflict. One malfunctioned; the other was intercepted; no damage resulted. Britain is now the only European state absorbing direct Iranian retaliatory fire, while the Coalition of Hormuz-statement signatories has grown from seven to 22 without a single warship deployment.

Deep Analysis

In plain English

Every British government has a lawyer called the Attorney General who advises whether government actions are legal under international law. In 2003, the Attorney General eventually said the Iraq War was legal — so the government proceeded, and controversy centred on whether that advice was genuinely independent. This time, the Attorney General has said the operation does not accord with international law. The difference is that the government gave the US base access anyway, without the legal advice changing. This matters because it establishes a precedent that the government can act contrary to its own published legal opinion when alliance politics demand it — and because it creates a documentary record that future courts, inquiries, or parliamentary committees will find easier to work with than the contested advice trail from 2003.

Deep Analysis
Synthesis

Hermer's advice creates an evidentiary record that distinguishes the current UK position from every prior military intervention in living memory: the government acted with documented legal warning rather than despite legal uncertainty. This shifts future accountability from 'the government was misled about legality' — the Iraq template — to 'the government was told and proceeded anyway.' The Chatham House critique compounds this by arguing the defensive/offensive distinction is not merely contested but legally incoherent, potentially exposing specific ministers and officers to individual accountability under the ILC Articles on State Responsibility.

Root Causes

The structural cause is the absence of a UK War Powers Act. Unlike the US, where Congress holds constitutional declaration authority, British prime ministers can commit military assets through royal prerogative without parliamentary authorisation. This concentrates legal risk in the executive with no distributional accountability mechanism — meaning the legal advice was the only institutional check available, and it has been overridden without formal procedure.

What could happen next?
  • Risk

    ICJ or ICC proceedings against UK government officials for complicity in unlawful use of force are procedurally easier given the documented, unrevised contrary legal advice.

    Long term · Suggested
  • Precedent

    A sitting attorney general's published international law advice overridden by executive action weakens the constitutional norm that legal advice constrains royal prerogative in military matters.

    Long term · Assessed
  • Consequence

    Parliamentary opposition holds a clear legal hook for judicial review of the basing decision, given the existence of undisputed contrary attorney general advice.

    Immediate · Assessed
  • Risk

    US allies facing analogous basing pressure — Australia, Canada, Japan — may read the UK precedent as licence to override domestic legal advice under alliance pressure.

    Short term · Suggested
Sources:Chatham House·Middle East Eye·Middle East Eye
Mentions:Chatham House →Diego Garcia →Gulf Cooperation Council (GCC) →Iran →Coalition →US State Department →National Security Council (Iran) →Cyprus →Bahrain →United States →Interim Leadership Council →Gulf States (Saudi Arabia, UAE, Qatar, Kuwait, Oman, Bahrain) →Strait of Hormuz →Israel Defense Forces (IDF) →RAF Akrotiri →RAF Fairford →Lord Hermer KC →Middle East Eye →Keir Starmer →
First Reported In

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Chatham House· 22 Mar 2026
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Causes and effects
This Event
UK attorney general: war unlawful
The UK government's chief legal adviser assessed the US-Israeli operation as contrary to international law — advice Starmer overrode within 48 hours. The gap between legal counsel and political action parallels the Iraq War's Goldsmith controversy, while Iran's retaliatory strike on Diego Garcia within hours of the base authorisation made the consequences operational.
Led to
Corbyn bill demands vote before base use
Attorney General's advice that operations do not accord with international law strengthened the case for parliamentary oversight legislation.
Occurred 22 Mar 2026
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