The question whether the principle of subsidiarity can apply in a given legal or political order is not systematically addressed in subsidiarity research.1 An explanation is that the conditions under which subsidiarity can apply appear to be straightforward and undemanding. They are already met, it may seem, wherever there is a government hierarchy. Two levels suffice. Authority should then be allocated to, or exercised at, the lower level, according to the principle of subsidiarity. The premise of this article2 is that the applicability conditions of subsidiarity are not as straightforward and undemanding as may seem. One claim in this article is that the conditions vary with the specific conception of subsidiarity that is adopted. Not all conceptions presuppose a government hierarchy. Some conceptions presuppose an assistance relation between smaller and larger units of authority (Cahill 2017). Another claim is that the applicability conditions of these conceptions are not always met. And this is not necessarily a flaw of the legal order in question. In some legal orders, the principle of subsidiarity is simply out of place, inconsistent with the structure that these orders ought to have in light of principles of democracy and rule of law. It is therefore crucial, I propose, to study the conditions under which a conception of subsidiarity can apply and to examine whether those conditions are met, or could be met, by the legal order in which the principle is supposed to apply. Ideally, the literature should relate subsidiarity conceptions to types of legal orders. The conditions of applicability connect the two. Within the confines of this article, I cannot present a comprehensive theory of subsidiarity and the conditions of this principle's application, in which a typology of conceptions is related to a typology of legal orders. What I can do here, however, is illustrate a more integrated approach to subsidiarity in which conceptions and their conditions of application are confronted with kinds of legal order. The question that I shall address in this article is whether subsidiarity can apply in the case of the European Union. The answer to that question is surely important in itself (Section 3.2) but the aim here is also to develop, in the course of the case study, an integrated approach to subsidiarity and legal order. This approach can then be used and further developed in other cases. I shall argue that the applicability conditions of the hierarchical and the assistance conception of subsidiarity are not met in the case of the European Union (hereafter also: EU). I explain as well why the principle that is referred to as subsidiarity within EU law is not a principle of subsidiarity. It has the name but not the defining feature of the principle. I also ask whether the EU legal order should be transformed to make room for subsidiarity. I argue for a negative answer. In the final section, I collect the main ingredients of the integrated approach. The article is constructed as follows. In Section 2 I discuss two conceptions of subsidiarity and I infer conditions of application from them. I indicate that the literature so far lacks an integrated approach to subsidiarity. In Section 3 I introduce the case of the European Union. In Section 4 I argue that the applicability conditions of the two conceptions (outcome of Section 2) are not met in the case of the European Union (outcome of Section 3); I also argue that the EU legal order should not be rearranged to make room for subsidiarity. In Section 5 I argue that the principle that is codified in EU law is not a principle of subsidiarity. In Section 6 I return to the general discussion in the literature and draw conclusions. The concept of subsidiarity has a rich history (Føllesdal 1998; Cahill 2017). Its origins are dated back to Aristotle's political philosophy and to Catholic thought, among other sources. What I want to find out in this second section is whether it is justified to claim that there is one basic 'concept' of subsidiarity whose variations can then be further organized in multiple 'conceptions' (Dworkin 1978, 134). I also introduce two conceptions of subsidiarity that can be found in the literature—the hierarchical and the assistance conception—and infer applicability conditions from them.3 I argue in this Section 2.4 that the subsidiarity literature so far lacks transparent lines of reasoning about subsidiarity's applicability. The subsidiarity literature appears to support an affirmative answer to the question whether it is justified to claim that there is a 'concept' of subsidiarity, a defining feature shared by the various 'conceptions' of subsidiarity. In for example Da Silva's helpful entry 'Subsidiarity' in the Encyclopedia of the Philosophy of Law and Social Philosophy, it is argued that lawyers and political scientists use many versions of the principle of subsidiarity (Da Silva 2023b, 1) but it is suggested that they nevertheless accept subsidiarity's 'defining feature' (Da Silva 2023b, 4), which is 'its "presumption" of local or primary control.' (Da Silva 2023b, 5) Cahill's analysis of the use of subsidiarity by EU lawyers agrees with Da Silva's suggestion. In 'Theorizing subsidiarity. Towards an ontology-sensitive approach,' Cahill discusses several 'diverging positions' adopted by 'scholars of subsidiarity in the European context,' but these positions are nevertheless viewed as 'derived from the same starting-point: that subsidiarity is concerned with the distribution of decision-making authority between "higher" and "lower" levels, according to certain criteria,' with a 'preference for the lower units' (Cahill 2017, 203, 202 and 206). In a later publication, Cahill reformulates and strengthens this conclusion: 'If there is anything that everybody seems to agree on in relation to subsidiarity, it is that it consists in a preference for proximity.' (Cahill 2021, 129) Based on these overview articles by Da Silva and Cahill, I take here as accepted that most lawyers and political scientists presuppose the same general concept of subsidiarity, which entails a preference for, or a presumption in favor of, the allocation of authority to, and/or the exercise of authority at, units of government that are closer to the governed. If this concept is specified in terms of higher and lower levels of government, then we have what I call a hierarchical conception of subsidiarity. According to Elazar, subsidiarity 'is designed to soften hierarchy by vesting and protecting the powers of its lower levels.' (Elazar 2001, 42) The hierarchical conception's condition of application appears to be straightforward.4 This conception has one applicability condition: the conception can apply wherever there is a government hierarchy. If subsidiarity indeed 'is designed to soften hierarchy,' then surely such a hierarchy needs to be present for subsidiarity to be applicable. The hierarchical conception is widely shared by lawyers and political scientists (Cahill 2017). However, the vocabulary of higher and lower and levels is not preferred by all subsidiarity scholars.5 In an interesting contribution to the literature, Cahill has even argued that historical texts on subsidiarity reveal that the contemporary emphasis on hierarchy and levels is unjustified. This is also reflected in subsidiarity's etymology, according to Cahill. The Latin word 'subsidium' means assistance or support. In Cahill's own alternative conception, subsidiarity therefore presupposes an assistance relation between a smaller 'primary unit' of authority and a larger 'subsidiary unit' of authority, whereby the latter gives subsidium or assistance to the former. Giving subsidium does not mean that the larger, subsidiary unit has more authority or is positioned on a higher level in a government hierarchy. On the contrary, the idea is that the smaller unit is primary qua authority whereas the subsidiary unit only has extra power or capacity: 'The key insight is that authority is embedded in the primary units because of their particular nature and purpose, and subsidiary units can intervene in relation to primary units not because of a superior claim to authority but because of a superior capacity to help the primary unit achieve its goals.' (Cahill 2017, 213) This reference to the nature or purpose of units of authority has led commentators to refer to Cahill's approach as 'natural' (Da Silva 2023b, 3). Cahill (2017) further specifies this assistance conception of subsidiarity in four precepts. (1) It is up to the primary unit of authority to ask for assistance. (2) The subsidiary unit only gives assistance if the primary unit asks for it. (3) The assistance given by the subsidiary unit has to be for the benefit of the primary unit. (4) The primary unit has to decide whether the assistance has been beneficial, for example by periodically reviewing the assistance provided by the subsidiary unit. These features clarify the dominant position of the smaller unit. They indicate as well that the conception falls within the general concept of subsidiarity. What distinguishes the assistance conception from the hierarchical conception is that the former, unlike the latter, does not presuppose that the smaller and larger units comprise levels of one hierarchical government system.6 It presupposes a relationship of assistance between primary and subsidiary units of authority instead. So with this assistance conception come two conditions, I argue, which both have to be met for the conception to be applicable. The first is that the smaller units of authority have a nature or purpose that justifies that authority is allocated to them. The second is that the larger unit of authority has the capacity to assist the smaller unit of authority. Federalism, however, is antihierarchical, based on covenant-based principles that see the proper political organization as a matrix with larger and smaller arenas but not higher and lower: a vitally important distinction since larger and smaller do not imply any ranking of degree of importance—for some purposes a larger arena is the most important and for others a smaller arena is. (Elazar 2001, 42) Elazar's suggestion that subsidiarity is misplaced in federations, also raises questions about other non-hierarchical contexts of government. Subsidiarity is claimed to apply in international law (Føllesdal 2013) and—more specifically—in certain international human rights regimes (Besson 2016). These possible 'domains' (Da Silva 2023b, 1) or 'contexts' (Besson 2016, 87) of subsidiarity are not hierarchically structured, or at least less so than the multilevel government context that is usually associated with the case of a nation state or country. In this regard it is interesting to notice that some subsidiarity scholars view the nation state context as the standard context of subsidiarity. 'Perhaps the principle's most obvious implications are for constitutional ordering within states,' Barber and Ekins (2016, 5) write. Da Silva accepts this (2023a, 92). Again, why the implications are most obvious for states, is not clear. Is it because of the hierarchical context, which is largely absent in the international arena? But it is also absent, at least to a certain degree, in countries that are structured federally, such as the US and Canada, at least according to scholars such as Elazar. But the latter cases are not only paradigmatic cases of federations, they are also paradigmatic case studies of subsidiarity. What this brief overview suggests is that the literature does not systematically relate conceptions of subsidiarity to legal orders, whereas a more integrated approach would shed light on the issue—remaining only implicit in the literature now—which conception of subsidiarity can apply (best) in which kind of legal order. My objective in this article is to develop such an approach that integrates conceptions, their applicability conditions, and the structures of legal orders. The conclusion of this second section is that there is a concept of subsidiarity which can be further specified in at least two different conceptions of subsidiarity: a hierarchical conception and an assistance conception. With these conceptions come different conditions of application. Another conclusion is that the subsidiarity literature does not specify conditions of application; it does not systematically relate conceptions of subsidiarity to types of legal order. To check whether the two conceptions just introduced can apply in the case of the European Union, an overview of the main characteristics of the EU legal order is necessary. I do that right below in Section 3.3. In Section 3.4 I conclude that there are actually two possible locations for the principle of subsidiarity in the case of the EU, one within that order and one between this order and the national legal order of one of its Member States. I explain first why I think the case of the EU is an interesting illustration of the main argument of this article (Section 3.2). I have selected the case of the European Union for three reasons. The first is historical. It is widely accepted in the literature that the codification of subsidiarity in European law initiated a proliferation of publications on subsidiarity. Føllesdal (2013, 37), for example, writes that 'subsidiarity has emerged as a prominent concept in legal and political theory, not least due to its inclusion in the 1991 Maastricht Treaty on European Union.' EU subsidiarity is also credited for structuring the concept of subsidiarity. 'Any "modern" conception of subsidiarity originates in EU law,' Da Silva (2023a, 84) writes. So the EU appears to occupy a special place in contemporary subsidiarity research, although recent literature also concludes, as noted in Section 2.4, that the typical case to which subsidiarity applies is the nation state (Barber and Ekins 2016, 5; Da Silva 2023a, 92) and not some form of cooperation between, or (con-)federation of, such states, of which the EU is an example.7 The second reason is that there seems to be something wrong with the EU principle of subsidiarity. It appears to be dysfunctional (Fabbrini 2018; Cahill 2021, 131; Cahill 2017; Davies 2006).8 It has a very prominent place in EU law, namely in Article 5 of the Treaty on European Union, but it is rarely appealed to; and if it is, the outcome is usually considered to be disappointing (Fabbrini 2018; Cahill 2021, 131; Cahill 2017; Davies 2006). The explanation that is usually given is that individual actors, including the judges of the European Court of Justice, are reluctant to apply the principle, presumably for political reasons (Fabbrini 2018). Subsidiarity is even feared to lead—counterproductively—to more 'centralization' or 'integration' in the hands of 'Europhiles' and 'pragmatists' (Cahill 2021, 131). But such political explanations are advanced before conceptions of subsidiarity, their conditions of application, and the structure of the legal order are considered. This brings me to the final reason. The third reason directly connects with the central line of argument in this article: it is far from clear whether there is a place for subsidiarity in the EU legal order.9 The EU case raises interesting issues in terms of subsidiarity's applicability conditions. The EU is sometimes characterized as a 'multilevel' system of government (Pernice 2009), which would imply that the hierarchical conception of subsidiarity can easily apply. However, the 'multilevel' vocabulary is used rather loosely and does not depict the EU legal order accurately, as I shall explain in Section 4.1. A further complication is that the relation between the EU and its Member States is characterized as 'non-hierarchical' (Pernice 2010) as well, also by authors who adopt the 'multilevel' metaphor. This inconsistency can be removed, I propose (Section 4.1), once the distinction between two possible locations for subsidiarity is made (Section 3.4). Legal orders are usually categorized by their source. Law is then either national (source: legislation) or international (source: treaty). According to this orthodox legal dichotomy, the law of European integration is international because it is treaty-based. However, orders can also be categorized by the kind of horizontal relations they bring under law, as Kant (2011) does. This produces a trichotomy in a legal universe populated by only persons and states: national law (relations between persons under a state's institutions), international law (relations between states) and cosmopolitan law (relations between a state and a person not under that state's institutions—i.e., a foreigner). In this trichotomy, the law of European integration is interpreted as cosmopolitan since it brings the relationship between an EU Member State and a national from another EU Member State under a uniform body of law (Ferry 2009; Wolthuis and Corrias 2021). Viewed in this light, EU law is international qua source and cosmopolitan qua content. I propose, therefore, that EU law can best be introduced by seeing some of its characteristics as implications of its cosmopolitan nature and others as consequences of its international origin. I show this here with respect to the content of EU law (Section 3.3.2), the institutional structure of the EU (Section 3.3.3) and the relation between EU law and national law (Section 3.3.4). EU internal market law forms the core of the law of European integration (Lenaerts and Van Nuffel 2011, chapter 1 and 195; ECJ case 26/62 (Van Gend Habermas 2012, 341). The terminology matters here. The precedence terminology affirms the non-hierarchical relation between European and national law. But it also emphasizes the cosmopolitan nature of European integration law, with its main aim to establish a uniform body of law for the European Union of states and persons. Ordinarily, it depends upon a nation state's own system of law whether international law is directly applicable and has precedence. However, within the context of the EU sovereign and the national sovereign, that issue cannot be decided by each Member State's system of constitutional law. EU law's precedence of application is the corollary of the specific character of European integration. An internal market simply cannot be realized if national instead of European law would have precedence. The internal market, which requires a set of rules that is interpreted and executed in a uniform manner within the entire EU, is simply unattainable if individual Member States could render its provisions inapplicable unilaterally by introducing national legislation.16 This characterization of the EU legal order invites us to distinguish between two possible locations for subsidiarity in the EU case. In the EU subsidiarity literature, the distinction is usually not made; but I think it should be made to avoid confusion.17 The point is that the relation between EU institutions and EU Member States is radically different in the two settings. The first location is within the EU legal order. The principle of subsidiarity operates as an intra-system principle in this order (i.e., if there is place for it). Within this order, the relation between EU institution and EU Member State is that between sovereign and subject, as indicated above in Section 3.3.3. Hereafter, this location of subsidiarity is referred to as the "one-system context". The second location is between the EU legal order and the national legal order. The principle of subsidiarity operates as an inter-system principle in this context (if it turns out to be applicable). Within this context, we have two distinct legal orders, each with a legislative institution that is sovereign with respect to certain matters. Here, the relation between the EU legislature and the national legislature is that between sovereign and sovereign (Section 3.3.4). Hereafter, this context of subsidiarity is referred to as the "two-system context." For most EU lawyers and political scientists, the applicability of the hierarchical conception of subsidiarity in the case of the EU may seem to be a non-issue. For it is not uncommon at all to talk and write—and think—about the EU as a 'multilevel' system of government (Pernice 2009). The image of multiple levels suggests that EU institutions form the top of a governmental pyramid, with right below them the Member State governments and, even further down, these states' provinces, Gewesten or Länder, etc. In the case of the EU, the applicability condition of the hierarchical conception seems easily met. However, the multilevel metaphor is used rather loosely and authors do not distinguish between the two contexts of subsidiarity distinguished in Section 3.4. Hence confusion lies in wait. Take for example the article 'The Treaty of Lisbon: Multilevel Constitutionalism in Action' (Pernice 2009). The author arrives first at the conclusion that the EU is a multilevel system of government (2009, 373) and then introduces the principle of subsidiarity against this multilevel background (2009, 391–392). However, Pernice also expresses doubts about the hierarchical metaphor (2009, 383) and qualifies EU law and national law as 'formally autonomous' systems too (2009, 383). These doubts and inconsistencies are not fed back into the analysis of subsidiarity. To complicate matters even further, in a later article Pernice characterizes the EU law-national law relation unequivocally as 'non-hierarchical' (2010, 57). The confusion can be removed, I propose, once the distinction between the two separate contexts of subsidiarity is drawn. Pernice's later analysis of the 'non-hierarchical' (2010, 57) relation between European and national law is in line with the doctrine summarized in Section 3.3.4, at least if it is confined to the two-system context. The 'multilevel' view of the EU is, however, an inadequate description of the one-system context. As I have tried to clarify in Section 3.3.3, the EU legal order does not have multiple levels of authority. The Member States are subjects within that order. They are not EU authorities and hence also no lower level EU authorities. This means that the hierarchical conception's applicability condition is not met in the one-system context. Hence, the hierarchical conception cannot operate as an intra-system principle within this context. There is only one level of government and hence it is impossible to apply the hierarchical conception of subsidiarity. Within the one-system context, authority can only be exercised by the EU institutions.18 The hierarchical conception's applicability condition is also not met in the context of the two-system context. Here the difficulty is that there are two distinct systems of law that are non-hierarchically related to each other, as specified in Section 3.3.4. So, the hierarchical conception cannot operate as an inter-system principle either. Whereas there are no multiple levels of authority in the one-system context, there is no hierarchical relation between systems in the two-system context. As indicated in Section 2.3, the assistance conception as defended by Cahill has two conditions of application. The smaller units of authority have to have a nature and purpose that justifies that authority is allocated and/or exercised by them; the larger unit of authority has to have the capacity to assist the smaller unit of authority. With respect to the first condition, Cahill (2017, 217) 'proceeds on the assumption' that the states are the primary units and that EU institutions comprise the subsidiary unit. Recall that a unit qualifies as the primary unit of authority because of its 'particular nature and purpose' (Cahill 2017, 213). According to Cahill it can depend on the 'circumstances' whether a certain unit qualifies as a primary or secondary unit of authority. In the circumstances of the EU, Cahill (2017, 216–217) assumes that the state is the primary unit and the EU the subsidiary unit. In light of Section 3.3.3, however, this assumption is unwarranted in the one-system context. The reason is that within that context the EU Member States are not units of authority at all but subjects. Within the one-system context, only EU institutions have a valid claim to authority. The EU legislative institutions, in which representatives of the Member States and their nationals are seated, have been se
A.J. Wolthuis (Sun,) studied this question.