Skip to main content


Log in

Just War Theory, Legitimate Authority, and Irregular Belligerency

  • Published:
Philosophia Aims and scope Submit manuscript


Since its earliest incarnations, just war theory has included the requirement that war must be initiated and waged by a legitimate authority. However, while recent years have witnessed a remarkable resurgence in interest in just war theory, the authority criterion is largely absent from contemporary discussions. In this paper I aim to show that this is an oversight worth rectifying, by arguing that the authority criterion plays a much more important role within just war theorising than is commonly supposed. As standardly understood, the authority criterion provides a necessary condition for the justification of the resort to war, but has no bearing on the question of permissible conduct in war. In opposition, I argue for an alternative interpretation of the criterion, which attributes to it a fundamental role in assessing this latter question. With this revised interpretation in place, I then demonstrate its advantages by applying it to the practical issue of armed conflicts that are initiated and fought by non-traditional belligerents. While several theorists have recognised that this common feature of modern armed conflict poses a challenge to mainstream just war theory in general—and to the authority criterion in particular—I argue that existing discussions frequently misconstrue the nature of the challenge, since they assume the standard interpretation of the authority requirement and its role within the theory. I then show that the revised interpretation provides a clearer account of both the challenge posed by non-traditional belligerency and the kind of response that it requires.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Similar content being viewed by others


  1. On this point see, among others, Langan (1984), Neff (2005), Russell (1975) and Johnson (2003). The authority criterion, or something closely analogous to it, was also a central component of Confucian approaches to the morality of warfare (Twiss and Chan 2007).

  2. Others who have noted this lacuna include Coates (1997), Fabre (2008), Finlay (2010) and Lang et al. (2013).

  3. I leave aside here the more recently emphasised fields of justice in ending wars (jus ex bello) and justice following war (jus post bellum).

  4. For a useful survey and comparison of different accounts of jus ad bellum, see Toner (2010).

  5. The criterion is also variously referred to in the literature as the ‘right’, ‘proper’, ‘competent’ or ‘sovereign’ authority requirement.

  6. For an overview of the equality thesis and the debate surrounding it, see Rodin and Shue (2008a).

  7. This interpretation is particularly reinforced on an orthodox approach to just war theory, which hold that these two fields are independent of one another.

  8. See Toner (2010).

  9. On the distinction between external and internal constraints on the resort to war, see Buchanan (1999).

  10. See, for example, Fotion (2007: 18–20), Quinlan and Guthrie (2007: 13), Orend (2000: 87), Regan (1996: Ch.2), Syse and Ingierd (2005).

  11. For example, the few discussions of applying the authority criterion in practice predominantly focus on the extent to which the President of the United States has the legal authority to take the nation to war without congressional approval. Christopher (2004: 87–88), Orend (2000: 97), Regan (1996: Ch.2).

  12. A structurally similar, though substantively distinct, version of the argument that I set out in the next three sections has also been suggested, albeit quite briefly, by Christopher Finlay (2010: Section III). My goal in this paper is to develop a more detailed and precise version of the argument, and to then explore its wider implications for just war theorising.

  13. Jeff McMahan has done most to argue for this conclusion (McMahan 2009: Chs. 1–2). For discussion, see the exchange between McMahan and Michael Walzer published in Philosophia. McMahan (2006a, b) and Walzer (2006b).

  14. For a useful collection of papers on this topic, see Rodin and Shue (2008b).

  15. See Walzer (2006a: 144–145).

  16. Versions of this argument have been put forward, independently, in Walzer (2006a: 37) and Hurka (2007).

  17. This problem is raised in McMahan (2009: 52).

  18. In addition, Asa Kasher and Amos Yadlin have argued that entering military service does not alter the normative situation between a citizen and their state, so that the state is not permitted to impose additional risks on their military personnel simply in virtue of their combatant status. Kasher and Yadlin (2005: 17).

  19. In addition to the Equality Thesis, the orthodox principle of non-combatant immunity has also been shown to be difficult to reconcile with our more general views about permissible killing (Frowe 2014: Chs. 6–8). If so, this reveals that the standard norms of conduct in war may also be more restrictive than those that govern harming in other contexts.

  20. The Discontinuity Thesis is similar to a view Seth Lazar labels ‘exceptionalism’. See Lazar (2014).

  21. For example, both Henry Shue and Michael Walzer each, independently, endorse a version of the Discontinuity Thesis (Shue 2008; Walzer 2006b). Judith Jarvis Thomson and Frances Kamm have also, independently, suggested versions of it, albeit without explicit endorsement (Thomson 1991: 297; Kamm 2012: 27).

  22. Neff (2005: 13–20). Neff does note that a small minority of cultures, such as the Innuit, do seem to lack a strong distinction between war and other forms of violence.

  23. I offer support for this claim in the section entitled “Classical Just War Theory and the Authority Criterion”.

  24. For a book length discussion of this contrast, see Fiala (2010).

  25. Jeff McMahan also notes this requirement (McMahan 2009: 31).

  26. As George Fletcher puts it, “not every shootout at the OK Coral qualifies.” (Fletcher 2002: 3).

  27. David Luban raises a similar problem regarding demarcating the boundary between the application of human rights law and the humanitarian law of armed conflict (Luban 2008: 276–280).

  28. Helen Frowe makes a similar point, suggesting that one function of the authority criterion is to define what counts as war (Frowe 2011: 59, 2014: 157–158). However, Frowe does not provide an account of why it morally matters that war be defined in such terms. It is this missing element that I aim to provide in this paper.

  29. Moseley does not present this claim as an interpretation of the role of the authority criterion.

  30. A similar point has also been suggested, independently, by Cecile Fabre and Christopher Finlay (Fabre 2012: 160; Finlay 2010). My aim in this paper is to provide a more developed explanation of why this is the case.

  31. I borrow the notion of ‘logical priority’ from Anthony Coates, who briefly suggests a similar interpretation of the authority criterion to my own in the context of his discussion of terrorism (Coates 1997: 123–124). Coates points out that it is problematic to understand the wrongfulness of terrorism in terms of violations of the just war principle of non-combatant immunity, because non-combatants immunity is a war-specific notion, implying that terrorists are engaged in war and are entitled to moral evaluation under the norms of just war theory. (For a similar point, see Goodin 2006: Ch.1). After raising this worry, Coates then concludes “that if any criterion of war merits greater application to terrorism than any other…it is the logically prior principle of legitimate authority.” (124). However, Coates does not provide an explicit account of why invoking the authority criterion is meant to resolve the worry, or why the criterion is ‘logically prior’ in the manner claimed. Moreover, in the majority of his discussion of the authority criterion (125–145) Coates retreats from the more expansive interpretation that he initially suggests, reverting instead to the standard, ad bellum interpretation. In this paper I aim to have provided the necessary arguments for expanding the role of the authority criterion in the manner that Coates alludes to. Furthermore, if successful, my arguments show that that this expansion is not necessitated merely by specific practical worries about terrorism. Rather, the criterion is required to play this additional role for more theoretical reasons, in order to prevent just war theory from running into a fatal problem of moral indeterminacy and incoherence. If correct, this shows that Coates’ and Goodin’s worry about excluding terrorism from just war evaluation is a symptom of a much more general issue.

  32. For example, the Correlates of War Project, which provides a major source of data for the empirical study of warfare, classifies wars as sustained combat, involving organised forces, resulting in at least 1000 combat deaths per 12-month period (Sarkees 2010).

  33. The formulation here is intended to allow for the possibility that in bello permissions may apply asymmetrically to opposing parties in an armed conflict, since one party may satisfy the authority criterion (and so be subject to norms of jus in bello) whereas the opposing party may not (and so be subject to ordinary norms of interpersonal harming.) For example, in the case of a recognised state engaging in armed conflict with a non-state entity, such as a terrorist organisation. Term this the unilateral reading of the revised authority criterion. By contrast, the quote from Orend’s suggests an alternative bilateral reading, which requires the authority criterion to be satisfied by both belligerents in order for war-specific norms to apply to either. Both readings seem defensible, though my intuitions favour the unilateral reading. But for our purposes we need not settle the matter here. The main claim that I defend and elaborate upon in this in this paper—that fighting on behalf of a legitimate authority is a necessary condition for evaluation under the norms of jus in bello—is consistent with either reading. (The extent to which it approaches a sufficient condition does vary depending on the reading.) In addition, it is worth pointing out that, on either reading, the fact that a non-state entity fails to qualify as an authority need not entail that it is unjustified in fighting against a state (since its violence could be justified in terms of ordinary norms of interpersonal harming, such as self-defence). Nor does a non-state entity’s failure to qualify entail that its state opponent is justified in fighting against it, since such measures would remain subject jus ad bellum requirements. Thanks to an anonymous reviewer for pressing me to clarify these points.

  34. See, for example, Begby et al. (2012: 331). More broadly, proponents of the ‘new wars’ thesis, such as Mary Kaldor, argue that the diversity of actors involved in modern armed conflict poses deep challenges to normative international political theory more generally (Kaldor 2007). For proposals as to how the norms of war may be adapted to apply to modern war, see Gilbert (2003), Gross (2009) and Kasher and Yadlin (2005).

  35. See Heinze and Steele (2009).

  36. See Fotion (2006) and (2007: Ch.9).

  37. Fotion does not explicitly endorse an orthodox conception of jus in bello. However, such a commitment can be inferred from what he does say on the topic. For example, he writes “it is easy to separate that part of a theory of exception having to do with starting a war (justice of the war) and the protracted period of time that follows once the war is started (justice in the war).” (2007: 21). Fotion also endorses a view of the in bello discrimination and proportionality requirements that are equally satisfiable by combatants who participate in just and unjust wars (2007: 21–22). Thus, taken together, it seems fair to attribute to Fotion a commitment to the orthodox Equality Thesis.

  38. The criterion remains applicable to state actors engaged in armed conflict with non-state actors under JWT-I. Fotion also relaxes the criterion of reasonable prospect of success in JWT-I (Fotion 2007: 120).

  39. See Reichberg (2013).

  40. See Reichberg (2013: 181–185). This point is also stressed in, among others, McMahan (2012), Neff (2005: 63), Reichberg (2008) and Steinhoff (2012).

  41. See O’Donovan (2003: 22).

  42. This appears to have been Augustine’s view, as well as that of St. Ambrose. See Langan (1984) and Swift (1970: 537).

  43. See Neff (2005: 59–62), Reichberg (2013: 189) and Thompson (1996).

  44. Thompson (1996: 677–679). George Fletcher points out that a successful invocation of the medieval common law defence of se denfendendo resulted only in the defendant’s avoidance of the punishment of execution, while conceding the wrongfulness of the act. The successful defendant was still required to give up property to the crown by way of recompense for the homicide. He notes, “Until the Statute of Henry VIII, passed in 1532…there was no theory of self-defense that rendered a killing fully lawful, justifiable and therefore free of the taint that affected excusable homicide.” (Fletcher 1990: 171).

  45. For contemporary arguments for a similar conclusion, see Norman (1995) and Rodin (2002).

  46. This thought is endorsed by Elizabeth Anscombe, the most influential recent proponent of a classical conception of just war, who writes that “The right to attack with a view to killing is something that belongs only to rulers and those they command to do it” (Anscombe 1981: 53) (emphasis added). Michael Thompson makes a similar point, arguing that “premodern practice,…restricted justified killing to that legitimately performed by agents of the state.” (Thompson 1996: 678).

  47. James Turner Johnson makes a similar point, noting that within classical just war theory “There is a fundamental moral difference between the use of the sword by one in sovereign authority or on his behalf and the use of the sword by a private individual. The former may wage bellum, which is the use of the sword on behalf of the common good; the latter may not.” (Johnson 2003: 9–10).

  48. Kutz (2005). For other broadly collectivist approaches, see Fletcher (2002), Meisels (2012) and Zohar (1993).

  49. Kutz suggests that he is committed to this interpretation (2005: 179).

  50. On this point, see Lichtenberg (2008).

  51. See Lazar (2013).

  52. For useful introductions to the concept of authority, see Raz (1990) and Shapiro (2002).

  53. See Estlund (2007).

  54. This seems to have been Augustine’s view (St. Augustine 1988: Bk.1. Ch.21). Graham Parsons has recently put forward an explicit version of this argument. See Parsons (2012).

  55. For arguments that states often lack the authority that they claim for themselves see, for example, Green (1988), Simmons (2002) and Raz (1979: Ch.12).

  56. I discuss this objection in more detail in an unpublished paper entitled ‘Liability, Community, and Just Conduct in War.

  57. My thanks to Daniel Viehoff, James Lenman and Stephen Wright for extremely helpful comments on earlier drafts of this paper.


  • Anscombe, G. E. M. (1981). War and murder. In The collected papers of G.E.M. Anscombe. Volume three: Ethics, religion and politics (pp. 51–61). Oxford: Blackwell.

    Google Scholar 

  • Begby, E., Reichberg, G., & Syse, H. (2012). The ethics of war. Part II: contemporary authors and issues. Philosophy Compass, 7(5), 328–347.

    Article  Google Scholar 

  • Buchanan, A. (1999). The internal legitimacy of humanitarian intervention. Journal of Political Philosophy, 7(1), 71–87.

    Article  Google Scholar 

  • Christopher, P. (2004). The ethics of war and peace: An introduction to legal and moral issues (3rd ed.). New Jersey: Prentice Hall.

    Google Scholar 

  • Coates, A. J. (1997). The ethics of war. Manchester: Manchester University Press.

    Google Scholar 

  • Estlund, D. (2007). On following orders in an unjust war. Journal of Political Philosophy, 15(2), 213–234.

    Article  Google Scholar 

  • Fabre, C. (2008). Cosmopolitanism, just war theory and legitimate authority. Ethics and International Affairs, 84(5), 963–976.

    Article  Google Scholar 

  • Fabre, C. (2012). Cosmopolitan war. Oxford: Oxford University Press.

    Book  Google Scholar 

  • Fiala, A. (2010). Public war, private conscience: The ethics of political violence. London: Continuum.

    Google Scholar 

  • Finlay, C. (2010). Legitimacy and non-state political violence. Journal of Political Philosophy, 18(3), 287–312.

    Google Scholar 

  • Fletcher, G. P. (1990). Defensive force as an act of rescue. Social Philosophy and Policy, 7(2), 170–179.

    Article  Google Scholar 

  • Fletcher, G. P. (2002). Romantics at war: Glory and guilt in the age of terrorism. Princeton: Princeton University Press.

    Google Scholar 

  • Fotion, N. (2006). Two theories of just war. Philosophia, 34, 53–64.

    Article  Google Scholar 

  • Fotion, N. (2007). War and ethics: A new just war theory. London: Continuum.

    Google Scholar 

  • Frowe, H. (2011). The ethics of war and peace: An introduction. Abingdon: Routledge.

    Google Scholar 

  • Frowe, H. (2014). Defensive killing: An essay on war and self-defence. Oxford: Oxford University Press.

    Book  Google Scholar 

  • Gilbert, P. (2003). New terror, new wars. Washington: Georgetown University Press.

    Google Scholar 

  • Goodin, R. E. (2006). What’s wrong with terrorism. Cambridge: Polity Press.

    Google Scholar 

  • Green, L. (1988). The authority of the state. Oxford: Oxford University Press.

    Google Scholar 

  • Gross, M. (2009). Moral dilemmas of modern war: Torture, assassination, and blackmail in and age of asymmetric war. Cambridge: Cambridge University Press.

    Book  Google Scholar 

  • Heinze, E. A., & Steele, B. J. (2009). Introduction: Non-state actors and the just war tradition. In E. A. Heinze & B. J. Steele (Eds.), Ethics, authority and war (pp. 1–20). Basingstoke: Palgrave MacMillan.

    Chapter  Google Scholar 

  • Hurka, T. (2007). Liability and just cause. Ethics and International Affairs, 20(2), 199–218.

    Article  Google Scholar 

  • Johnson, J. T. (2003). Aquinas and luther on sovereign authority. Journal of Religious Ethics, 31(1), 3–20.

    Article  Google Scholar 

  • Kaldor, M. (2007). New and old wars: Organised violence in a global era (2nd ed.). Cambridge: Polity Press.

    Google Scholar 

  • Kamm, F. M. (2012). The moral target. Oxford: Oxford University Press.

    Book  Google Scholar 

  • Kasher, A., & Yadlin, A. (2005). Military ethics of fighting terror: an Israeli perspective. Journal of Military Ethics, 4(1), 3–32.

    Article  Google Scholar 

  • Kutz, C. (2005). The difference uniforms make: collective violence in criminal law and war. Philosophy and Public Affairs, 33(2), 148–180.

    Article  Google Scholar 

  • Lang, A. F., Jr., O’Driscoll, C., & Williams, J. (2013). Introduction. In A. F. Lang Jr., C. O’Driscoll, & J. Williams (Eds.), Just War: Authority, tradition and practice (pp. 1–19). Washington DC: Georgetown University Press.

    Google Scholar 

  • Langan, J. (1984). The elements of St. Augustine’s Just War Theory. The Journal of Religious Ethics, 12(1), 19–38.

    Google Scholar 

  • Lazar, S. (2013). Associative duties and the ethics of killing in war. Journal of Practical Ethics, 1(1), 6–51.

    Google Scholar 

  • Lazar, S. (2014). National-defence, self-defence, and the problem of political aggression. In S. Lazar & C. Fabre (Eds.), The morality of defensive war (pp. 11–39). Oxford: Oxford University Press.

    Chapter  Google Scholar 

  • Lichtenberg, J. (2008). How to judge soldiers whose cause is unjust. In D. Rodin & H. Shue (Eds.), Just and unjust warriors: The moral and legal status of soldiers (pp. 112–129). Oxford: Oxford University Press.

    Google Scholar 

  • Luban, D. (2008). War crimes: The laws of hell. In L. May (Ed.), War: Essays in political philosophy (pp. 266–288). Cambridge: Cambridge University Press.

    Chapter  Google Scholar 

  • McMahan, J. (2006a). The ethics of killing in war. Philosophia, 34(1), 23–41.

    Article  Google Scholar 

  • McMahan, J. (2006b). Killing in war: a reply to Walzer. Philosophia, 34(1), 47–51.

    Article  Google Scholar 

  • McMahan, J. (2009). Killing in war. Oxford: Oxford University Press.

    Book  Google Scholar 

  • McMahan, J. (2012). War. In D. Estlund (Ed.), The Oxford handbook of political philosophy (pp. 298–318). Oxford: Oxford University Press.

    Google Scholar 

  • Meisels, T. (2012). In defence of the defenceless: the morality of the laws of war. Political Studies, 60(4), 919–935.

    Article  Google Scholar 

  • Moseley, A. The philosophy of war. Internet Encyclopedia of Philosophy. Available at

  • Neff, S. C. (2005). War and the law of nations: A general history. Cambridge: Cambridge University Press.

    Book  Google Scholar 

  • Norman, R. (1995). Ethics, killing and war. Cambridge: Cambridge University Press.

    Book  Google Scholar 

  • O’Donovan, O. (2003). The just war revisited. Cambridge: Cambridge University Press.

    Book  Google Scholar 

  • Orend, B. (2000). Michael Walzer on war and justice. Cardiff: University of Wales Press.

    Google Scholar 

  • Orend, B. (2008). War. In E. N. Zalta (Ed.), The Stanford Encyclopedia of Philosophy. Fall 2008 Edition. Available at

  • Parsons, G. (2012). Public war and the moral equality of combatants. Journal of Military Ethics, 11(4), 299–317.

    Article  Google Scholar 

  • Quinlan, M., & Guthrie, C. (2007). Just war. New York: Bloomsbury.

    Google Scholar 

  • Raz, J. (1979). The authority of law: Essays on law and morality. Oxford: Oxford University Press.

    Google Scholar 

  • Raz, J. (1990). Introduction. In J. Raz (Ed.), Authority (pp. 1–19). Oxford: Oxford University Press.

    Google Scholar 

  • Regan, R. J. (1996). Just war: Principles and cases. Washington DC: Catholic University of America Press.

    Google Scholar 

  • Reichberg, G. (2008). Just war and regular war: Competing paradigms. In D. Rodin & H. Shue (Eds.), Just and unjust warriors: The moral and legal status of soldiers (pp. 193–214). Oxford: Oxford University Press.

    Google Scholar 

  • Reichberg, G. (2013). The moral equality of combatants—A doctrine in classical just war theory? A response to graham parsons. Journal of Military Ethics, 12(2), 181–194.

    Article  Google Scholar 

  • Rodin, D. (2002). War and self-defence. Oxford: Oxford University Press.

    Google Scholar 

  • Rodin, D., & Shue, H. (2008a). Introduction. In D. Rodin & H. Shue (Eds.), Just and unjust warriors: The moral and legal status of soldiers (pp. 1–18). Oxford: Oxford University Press.

    Google Scholar 

  • Rodin, D., & Shue, H. (Eds.). (2008b). Just and unjust warriors: The moral and legal status of soldiers. Oxford: Oxford University Press.

    Google Scholar 

  • Russell, F. (1975). The just war in the middle ages. Cambridge: Cambridge University Press.

    Google Scholar 

  • Sarkees, M. R. (2010). The COW typology of war: Defining and categorizing wars (Version 4 of the data). Resource document. Correlates of war project.

  • Shapiro, S. (2002). Authority. In J. Coleman & S. Shapiro (Eds.), The Oxford handbook of jurisprudence and philosophy of law (pp. 382–439). Oxford: Oxford University Press.

    Google Scholar 

  • Shue, H. (2008). Do we need a ‘morality of war’? In D. Rodin & H. Shue (Eds.), Just and unjust warriors: The moral and legal status of soldiers (pp. 87–111). Oxford: Oxford University Press.

    Google Scholar 

  • Simmons, A. J. (2002). Political obligation and authority. In R. L. Simon (Ed.), The Blackwell guide to social and political philosophy (pp. 17–37). Oxford: Blackwell Publishers.

    Chapter  Google Scholar 

  • St. Augustine. (1988). The city of god against the pagans. In R. W. Dyson (Ed.), Cambridge: Cambridge University Press.

  • Steinhoff, U. (2012). Rights, liability and the moral equality of combatants. Journal of Ethics, 16(4), 339–366.

    Article  Google Scholar 

  • Swift, L. J. (1970). St. Ambrose on violence and war. Transactions and Proceedings of the American Philological Society, 101, 533–543.

    Article  Google Scholar 

  • Syse, H., & Ingierd, H. (2005). What constitutes a legitimate authority? Social Alternatives, 24(3), 11–16.

    Google Scholar 

  • Thompson, M. (1996). Aquinas and Locke on self-defense. University of Pittsburgh Law Review, 57, 677–684.

    Google Scholar 

  • Thomson, J. J. (1991). Self-defense. Philosophy and Public Affairs, 20(4), 283–310.

    Google Scholar 

  • Toner, C. (2010). The logical structure of just war theory. The Journal of Ethics, 14(2), 81–102.

    Article  Google Scholar 

  • Twiss, S. B., & Chan, J. (2007). The classical Confucian position on the legitimate use of military force. Journal of Religious Ethics, 40(3), 447–472.

    Article  Google Scholar 

  • Walzer, M. (2006a). Just and unjust wars: A moral argument with historical illustrations (4th ed.). New York: Basic Books.

    Google Scholar 

  • Walzer, M. (2006b). Response to McMahan’s paper. Philosophia, 34(1), 43–45.

    Article  Google Scholar 

  • Zohar, N. (1993). Collective war and individualist ethics: against the conscription of self-defense. Political Theory, 21(4), 606–622.

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Jonathan Parry.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Parry, J. Just War Theory, Legitimate Authority, and Irregular Belligerency. Philosophia 43, 175–196 (2015).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: