Parliamentary approval for military action

Published Wednesday, May 13, 2015

The deployment of the Armed Forces is currently a prerogative power. Parliament has no legally established role and the Government is under no legal obligation with respect to its conduct. In 2011 the Government acknowledged that a convention had emerged whereby the House of Commons would have the opportunity to debate the deployment of military forces, prior to doing so, except in the event of an emergency. The defeat of the Government in a vote on military action in Syria in August 2013 was widely viewed as an assertion of Parliamentary sovereignty on such matters. Yet many have argued that the convention lacks clarity and remains open to interpretation and exploitation. In 2011 the Government committed to legislate on this issue but by the end of the 2010-2015 Parliament no proposals were forthcoming. Going forward proponents of a formalised role for Parliament have suggested adopting a parliamentary resolution as either an interim step or as a viable alternative to legislation. Establishing either is fraught with difficulties and arguably, therefore, makes the continuation and strengthening of the current convention more likely in the immediate future.

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The Royal Prerogative

The decision to deploy the Armed Forces in situations of armed conflict is currently a prerogative power. In the event of a declaration of war or the commitment of British forces to military action, constitutional convention requires that authorisation is given by the Prime Minister, on behalf of the Crown. Decisions on military action are taken within the Cabinet with advice from, among others, the National Security Council and the Chief of the Defence Staff.

In constitutional terms Parliament has no legally established role and the Government is under no legal obligation with respect to its conduct, including keeping Parliament informed. In practice however, successive Governments have consulted and informed the House of Commons about the decision to use force and the progress of military campaigns, although there has been little consistency in how that has been achieved.

Nor is the Government under any constitutional obligation to abide by the result of any Parliamentary vote on military action, although in reality it would be politically difficult to engage in military action without Parliamentary support.

Pressure for reform

Since 2003, and the decision to allow Parliament a vote on military action in Iraq, there has been increasing pressure for reform. In 2007 the Labour Government announced a package of constitutional reforms intended to strengthen democracy and accountability and establish a new relationship between the Government and the people. Among suggested reforms was the proposal that a resolution of the House be passed giving Parliament the right to approve “significant non-routine” deployments of the Armed Forces, albeit “to the greatest extent possible” and “without prejudicing the Government's ability to act to protect national security, or undermining operational security or effectiveness”. Those proposals were never implemented before the Labour government left office in 2010.

2011 parliamentary convention

In 2011 the Coalition Government suggested that, since 2003, a convention had emerged in Parliament that before troops were committed to military operations the House of Commons should have an opportunity to debate the matter. It also proposed to observe that Convention except when there was an emergency and such action would not be appropriate.

While the convention was broadly welcomed, there was some initial debate as to whether such a parliamentary convention could be said to exist. Between the Iraq vote in 2003 and the Government’s observations in March 2011 there had been no Government-tabled debate, or vote, on any deployment of the Armed Forces, including the commitment of significant numbers of British forces to Helmand province in Afghanistan in 2006. Even the deployment of forces in Libya, which happened in concert with the Government’s acknowledgement of the convention in March 2011, was not the subject of a prior parliamentary debate and vote, which led Professor Gavin Phillipson at Durham University to argue that Libya was “not a fully satisfactory precedent” for parliamentary approval.

Evolution of the convention

The first deployment of British military assets after the Libya campaign was in Mali in early 2013. That deployment was undertaken without any debate, or vote in Parliament which drew some criticism given the Government’s previous assurances, and once again raised questions over the credibility of the convention and what sort of deployments would be likely to trigger its use.

By the end of 2014 Parliament had been given the opportunity to debate, and vote, on the deployment of British forces on two further occasions. The first was in response to the alleged use of chemical weapons against civilians by the Assad regime in Syria in August 2013 and the second was in response to the actions of Islamic State (ISIS) in Iraq in September 2014.

The Government motion to deploy military forces in Syria in 2013 was defeated by 13 votes. Despite its defeat the Government stated that it would respect the will of the House, a move that was widely viewed as an assertion of Parliamentary sovereignty and a direct challenge to the Royal Prerogative on such matters. It also led many commentators to suggest that any future significant deployment of the Armed Forces would now be inconceivable without prior recourse to Parliament.

That view gained further credence following the decision to seek parliamentary approval for offensive military action against ISIS in Iraq in September 2014, in line with the newly adopted convention. On that occasion the House supported the deployment of military forces.

Has clarity been achieved?

The Syria vote in 2013 was, and continues to be, viewed by many as a turning point in the debate on parliamentary approval. Commentators have argued that the defeat of the Government laid to rest doubts over the convention’s existence and made the deployment of the Armed Forces without parliamentary approval, from a political perspective, virtually impossible in the future.

Yet, has clarity on the use of the convention been achieved? At issue now is not whether the convention exists at all, but when it will be triggered. On the basis of recent deployments a nominal threshold for parliamentary approval appears to have been established:

  • The possibility of premeditated military action exists.
  • Military forces are to be deployed in an offensive capacity.
  • Retrospective approval would be sought in emergency situations, where there was a need to protect a critical British national interest or to prevent a humanitarian catastrophe.
  • If the House is dissolved the Government would come to Parliament as soon as possible for a parliamentary debate on the matter.

However, as many commentators have observed, the spectrum of potential military operations is vast and ‘critical national interests’ can be broadly interpreted. The lack of established definitions therefore continues to cause unease for many, and has led several to argue that the Government retains considerable discretion on what meets the convention’s threshold thereby making the whole framework potentially open to interpretation and exploitation.

Prospects for the future

Despite the emergence of this new convention it remains the case that Parliament has no legally established role in approving the deployment of the Armed Forces.  A commitment to legislate was made by the then Foreign Secretary, William Hague, in 2011. By the end of the 2010-2015 Parliament no legislative proposals had been put forward by the Government.

However, the lack of progress on this issue in nearly four years remains a concern for many observers, most notably the Political and Constitutional Reform Select Committee who have long argued for Parliament’s role to be placed on a statutory footing. Several commentators, including the Committee, have called for an interim parliamentary resolution in order to “clarify some of the ambiguities that exist under current arrangements. Others have suggested that a resolution alone would address the issue of formalisation whilst also avoiding some of the complexities associated with legislation.

The problems of formalising Parliament’s role

Defining either a resolution or legislation in a way provides Parliament with a meaningful role, yet safeguards the Government and military’s capacity to act, is paramount. Yet it is fraught with difficulties and potentially raises more questions than it resolves. One of the main problems is that of definition and how to adequately define the sort of military action that would trigger Parliamentary involvement; under what circumstances the Government could invoke the “emergency caveat”; and whether the escalation of an operation should require fresh approval. Parliament’s access to information, including legal advice and intelligence, prior to making a decision would also have to be carefully set down. Placing Parliament’s role on a statutory basis also raises issues of justiciability and the potential for legal challenge in the courts. 


One of the biggest challenges in moving beyond the current convention is that all stakeholders, even within Government, have differing opinions on what they want a resolution or legislation to achieve. This dilemma also lies at the heart of the current convention and is one of the reasons advocates are pushing for a more formalised solution. There are no right or wrong answers and possibly this circle will never be squared. Achieving a solution acceptable to all will require immense political will and, as such, makes the continuation and strengthening of the current convention a much more likely prospect for the foreseeable future.

Commons Briefing papers CBP-7166

Author: Claire Mills

Topics: Armed forces, Constitution, Defence policy, Military operations, Parliament

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