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How does the UK go to war?

Air strikes carried out by the Royal Air Force in April 2018 – in conjunction with the United States Air Force and the Armée de l'Air – resulted in two days of debate in the House of Commons, with a focus on the legal and procedural means by which Her Majesty’s Forces are deployed. What role does and should Parliament play in military decision-making? Are the present constitutional arrangements adequate, or is there a need for reform?

Click on the icons below to read our authors' analyses of these questions.


In April 2018, following a suspected attack with chemical weapons on the Syrian town on Douma, British, American and French forces struck three strategic sites from the air. The Royal Air Force was deployed on the orders of the Prime Minister, having consulted Cabinet, in exercise of the Royal Prerogative powers vested in the Executive.


The legislature – Parliament – was not consulted on the matter (since there is no legal necessity for this), nor was its prior approval sought, owing to the speed with which it was necessary to act.


However, Parliament’s retrospective approval of the Government’s actions was not in doubt; the symbolic division in the House of Commons on the 16th April passed by 314 votes to 36. Despite this, the House still saw fit to debate Parliament’s role in future military deployments the next day.


The (again symbolic) vote following that second debate was more divided, with 317 Ayes to 256 Noes. It is not clear exactly what we should glean from those “No” votes, for the motion was simply “That this House has considered Parliament’s rights in relation to the approval of military action by British Forces overseas.” Nonetheless, it was clear at least from the tone of the debate that there is some appetite for some kind of new role for Parliament in the deployment of troops.


Many Members rehearsed the argument that consulting Parliament before military action is simply not feasible either because of the swiftness which such action requires, or because sharing intelligence in debate is self-evidently not sensible. It is not wise to forewarn one’s enemies of one’s strategy. Without such intelligence, of course, the debate becomes rather a pointless exercise.


But all too common a counter to this was that it had, since the invasion of Iraq in 2003, become the accepted custom that Parliament be consulted prior to any engagement taking place. This is not strictly true. On 20th March 2011, RAF Tornadoes and Royal Navy submarines undertook a bombing mission in Libya. Parliament was asked to record its approval only after the event, on the 21st March. It did so by 557 votes to 13.


But even if that argument is not factually accurate, there is clearly some appetite for it to be so. How would such a change work?


The only binding motions with legal effect which Parliament can pass come in the form of legislation. Those arguing for Parliament to have some formal role in military deployments are presumably, therefore, arguing that Parliament should legislate each time such action is proposed. Here, there is an obvious practical problem: it is inconceivable that a Bill could pass the necessary stages in both Houses with the expediency routinely required by military action.

Perhaps, then, they prefer that Parliament could formally authorise action – exceptionally – by some kind of resolution in both Houses. Certainly, this would be quicker than legislating, but this approach faces further issues immediately. Firstly, the Houses of Parliament “note”, “resolve” and “consider” subjects all the time – from Opposition Day debates to Early Day Motions. We would thus need some new set of rules (presumably given by legislation) as to which of these non-legislative motions were to have legal effect and which were not, with all the potential for Parliamentary mischief-making which that may entail.

Secondly – perhaps more seriously – even if some means of “quick authorisation” were to be developed, there remain the questions of what would count as a military action in need of Parliament’s explicit consent, and whose decision that would be. Each time a Trident submarine goes to sea? Each time the RAF is scrambled to deal with a threat to British airspace? Each time soldiers are deployed in a counter-terrorism role in the UK? Plainly, such a system – even at the fastest of Parliamentary speeds – would cripple our entire defence effort.


Changes of this type are, therefore, unworkable. But moreover, they appear unnecessary given that Parliament might already be said to have a “triple lock” on military activity. By different means, Parliament fully – indeed, existentially – reviews the armed forces every 5 years and every year, as well as having “emergency powers” in the event of its disapproval of a particular course of action.


Since the Glorious Revolution and the subsequent passage of the Bill of Rights in 1689,  “the raising or keeping a standing Army within the Kingdome in time of Peace unlesse it be with Consent of Parlyament” has been against the law. For this reason, Parliament considers an Armed Forces Bill every 5 years, giving its consent for the existence and scope of the Forces of the Crown. Most recently, in 2016, the Armed Forces Act passed through both its Second and Third Readings in the Commons without a vote, signalling Parliaments unanimous approval for the continuation of the Armed Forces as they had previously been constituted.

Secondly, Parliament controls the funding for the Armed Forces each year. Should it wish, Parliament could reduce or abolish this funding if it felt that the role of the Armed Forces should change or cease.


Finally, if those two means failed to thwart some unscrupulous Government in an irresponsible military policy, it is open to Parliament to bring a motion of no-confidence either in the Government as a whole (as on 28th March 1979 when the Callaghan Government was defeated by 311 votes to 310) or on a particular policy (as on 28th February 1980, when Callaghan moved "That this House has no confidence in the economic and industrial policies of Her Majesty's Government” but was defeated 268-327). The effect of such a motion passing is swift and decisive: the Government falls and (usually) a General Election follows.


The question which the Commons debated following the Syrian air strikes thus seems to have been answered already. Through the Armed Forces Acts, budgets, and the potential for confidence motions, the centuries-old constitutional arrangements provide Parliament the means of effective oversight of the military, to which any cumbersome new addition would add nothing.

Dr Robert Thomas is a scientist, writer and Executive Director of Accademia.

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