The Use of Military Force by the United Kingdom: the Evolution of Accountability

19 Pages Posted: 12 Dec 2018

Date Written: October 12, 2018


Accountability for decisions to go to war has evolved in particularly since the 2003 Iraq War, both in a democratic dimension, involving parliaments in deployment decisions, and in a rule of law dimension, enforced by courts. Both forms of accountability lead to a rebalancing of the powers of the executive and the other two branches of government. This chapter considers the evolution of democratic accountability in the United Kingdom, i.e. the competence of Parliament to debate and vote on the government’s decision to deploy the military. The chapter outlines the emergence of a constitutional convention requiring prior parliamentary approval for uses of military force (I), considering the practice in relation to recent military deployments, e.g. in Syria and Iraq. In this context, different regulatory approaches to military deployments and reform proposals are discussed. The chapter then discusses some uncertainties about the rules of the constitutional convention, such as the threshold of the approval requirement and its exceptions (II). Finally, the chapter reflects on the UK practice from a comparative perspective of the implementation of democratic accountability in Germany (III). The chapter critically reflects the lack of formality and malleability of the constitutional convention, resulting in an executive bias, and the obstacles to formalizing the constitutional convention. One particular concern is the courts’ potential role in reviewing executive war powers and the substantive legality of a military deployment. It is argued from a comparative perspective that some concerns about a further formalization of the constitutional convention may be overstated.

Keywords: military deployment decisions (United Kingdom), use of force, executive power in foreign policy, parliamentary vote, constitutional convention, royal prerogative, role of courts, constitutional democracies, military deployment decisions (Germany), Parliamentary Participation Act 2005 (Germany)

Suggested Citation

Ziegler, Katja S., The Use of Military Force by the United Kingdom: the Evolution of Accountability (October 12, 2018). University of Leicester School of Law Research Paper No. 18-09. Available at SSRN:

Katja S. Ziegler (Contact Author)

Leicester Law School ( email )

University Road
Leicester LE1 7RH, LE1 7RH
United Kingdom

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