The Legal Effects of Treaties in Domestic Legal Orders and the Role of Domestic Courts

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The Legal Effects of Treaties in Domestic Legal Orders and the Role of Domestic Courts

1. Introduction

This chapter explores the general stance of international law and domestic legal orders on the issue of the legal effects of treaties in the domestic legal arena. It seeks to provide the basis for adopting a more contextual and comparative approach to the approach adopted in EU law to questions pertaining to the legal effects of EU Agreements. This is particularly appropriate because the EU itself is composed of States which have adopted their own diverging domestic constitutional approaches to such issues. In this fashion the impact of the EU law construct on domestic constitutional orders can be more persuasively articulated. It is also intended as a corrective to many existing accounts of the legal effects of EU (and indeed non-EU) Agreements which are largely acontextual—either simply looking at the approach of the EU alone or, where a comparative dimension is brought into the frame, perhaps not providing a nuanced recap of extant practice.

The chapter is divided into three core sections. The first addresses the requirements imposed by international law as to the legal effects to be accorded to treaties in domestic legal orders. The second looks at the basic dichotomy in approach at the domestic constitutional level to giving legal effect to treaties. The final section briefly revisits two opposing theoretical constructs used to conceptualize the legal effects accorded to international law (particularly as employed in the treaty setting) before offering some more general reflections pertaining to the role of domestic courts in treaty enforcement.

2. The Dictates of International Law

2.1 The basic precept

The core precept of the law of treaties is the principle of pacta sunt servanda enshrined in Article 26 of the Vienna Convention on the Law of Treaties and which states that: ‘Every treaty in force is binding upon the parties to it and must be performed by them in good faith.’¹ But whilst treaties are to be performed in good faith, it remains the case that they are in principle no exception to the basic precept of international law that States are free to determine how they meet their international obligations.²

It is, indeed, rather striking that treaties do not as a general rule impose specific requirements as to how the substantive obligations that they lay out should be realized in the domestic legal orders of the Contracting Parties. There are several interlinked factors that have been adduced for this seemingly curious state of affairs. The core issue relates to the traditionally central tenet of international law, that of State sovereignty. As one scholar put it:

States consider that the translation of international commands into domestic legal standards is part and parcel of their sovereignty and are unwilling to surrender it to international control.³

Accordingly States, in principle, are said to be concerned with whether compliance with the treaty obligations takes place and not with how this does or does not come about.⁴ Related to this, is the fact that States have developed different approaches to seeking to ensure compliance with their treaty obligations which renders it all the less likely that treaties will expressly address themselves to how the obligations should be given effect internally.⁵ In short, international law leaves it to the domestic legal order to determine how it gives effect to its treaty obligations in the domestic legal arena. In this respect a recent detailed assessment concluded that there is no general obligation under general international treaty law, customary international law, or general principles of international law requiring States to open their courts for invocation of treaty norms by individuals.⁶ It is clear that however effect is to be given domestically to treaty obligations, a State cannot invoke its internal law as justification for a failure to perform.⁷

There are, however, exceptions to the basic rule in that in the case of some treaties States have sought to constrain this freedom of manoeuvre by stipulating some requirements as to how treaties, or specific provisions, are to be given effect in the domestic legal order. Thus, for example, treaties, and specific treaty provisions, can be drafted expressly to require the Contracting Parties to enact internal implementing legislation. An example of a treaty containing an express requirement for legislation to give effect to its provisions is the Genocide Convention (1948) (Art 5). The Geneva Conventions (1949), for their part, constitute examples of treaties containing specific provisions calling for implementing legislation.⁸ And, indeed, in the general sphere of international criminal law it is evident that treaties have become increasingly exigent.⁹ The UN Convention against Torture (1984), for example, contains a provision requiring each party to ‘take effective legislative, administrative, judicial or other measures to prevent acts of torture in any territory under its jurisdiction’ as well as a provision requiring the criminalization of certain acts.¹⁰ Various human rights treaties also contain provisions stipulating that the Contracting Parties undertake to adopt legislative or other measures to give effect to the relevant rights where this is not already provided for in existing legislative or other measures.¹¹ In addition to this, there are examples of treaties—notably in areas such as friendship, commerce, and navigation, bilateral investment treaties, as well as treaties pertaining to patents, copyrights, and trademarks—that expressly require access to local courts.¹²

2.2 Pronouncements of the World Court: from Danzig to Avena

Whilst it is recognized in international law that a treaty can require that it be directly applicable in domestic courts,¹³ whether a particular treaty could indeed be relied on by individuals in a domestic court has only once been addressed by the Permanent Court of International Justice (PCIJ). At issue in the Danzig Advisory Opinion¹⁴ was an international agreement between Poland and the Free City of Danzig, which concerned the transfer of Danzig railway officials into the service of the Polish Railways Administration (PRA) and regulated their employment conditions. Various actions against the PRA for pecuniary claims by railway officials who had passed into its service were then brought in the Danzig courts based on the Agreement. The Polish Treasury raised objections on the ground that the Danzig courts had no jurisdiction and Poland informed the High Commissioner of the League of Nations at Danzig that it would not comply with judgments based on the Agreement. This ultimately led to the Council of the League of Nations seeking an Advisory Opinion.

The PCIJ commenced by identifying the point in dispute as being whether the Agreement formed part of the series of provisions (the contract of service) governing the legal relationship between the PRA and the Danzig officials. The answer to this question was considered to depend on the intention of the parties. The Court asserted ‘It may be readily admitted that, according to a well-established principle of international law … an international agreement, cannot, as such, create direct rights and obligations for private individuals.’ However, the Court added, ‘it cannot be disputed that the very object of an international agreement, according to the intention of the contracting Parties, may be the adoption by the Parties of some definite rules creating individual rights and obligations and enforceable by the national courts.’¹⁵

But the Court seemed to cast doubt on the aforementioned assertion when it went on to find that the wording and the general tenor of the Agreement ‘show that its provisions are directly applicable as between the officials and the [PRA]’ and that its object was the creation of’a special legal regime governing relations between the [PRA] and the Danzig officials’.¹⁶ The Court seemed to be overlooking its earlier statements of treaties not being able to create direct rights and obligations for private individuals and it being the adoption of definite rules by the parties that creates the individual rights enforceable in national courts. This confusion appeared to be further cemented when it concluded that the provisions of the Agreement formed part of the contract of service and that the Danzig officials had a right of action against the PRA based on the Agreement. The Danzig courts did not appear to have any domestic legal difficulties in giving effect to the Agreement,¹⁷ and this may explain the apparent dissonance in the reasoning of the PCIJ.¹⁸

Despite the aforementioned ambiguity in the reasoning, the Advisory Opinion has been considered as authority for the proposition that States can conclude treaties containing undertakings as to their domestic application and that they will be under an international obligation to ensure that the treaty is enforceable in the domestic courts.¹⁹ And the Danzig Opinion affirmed that this can be so even absent an express undertaking to that effect, providing it can be deduced from the intention of the parties as evinced by the content of the agreement. It seemed that this would be a rare occurrence, the Court having underlined the special legal regime that the Agreement had created. Indeed, that Agreement was certainly unique in nature, concerning as it did the conditions of the transfer of employees into the service of the PRA and regulating their employment conditions.

Whilst the interwar years had already seen the emergence of treaties that did have the protection of the individual as their objective,²⁰ States were in principle not drafting treaties which one could realistically say were intended to create individual rights and obligations enforceable by national courts. And yet few could then have anticipated the transformation that was to take place in the subject matter of treaty-making in the post-Second World War era, particularly via the explosion in legally binding international and regional human rights treaties which had the protection of the individual as their leitmotif.²¹ This is not to suggest that such treaties were drafted expressly to impose an international law obligation that they should be domestically judicially enforceable, but it nonetheless raised the possibility that where judicial organs and supervisory organs existed they might well reach such a finding following the path that the Danzig Advisory Opinion had opened up. Before turning to the pronouncements of such bodies, it is important briefly to note two rulings concerning the 1963 Vienna Convention on Consular Relations that are the closest the PCIJ’s successor, the International Court of Justice (ICJ), appears to have come to engaging with the issue that arose in Danzig.²² Here the US failure to give timely notification to foreign nationals of their right to consular protection was held to violate individual rights created by Article 36 of the 1963 Convention. The application of a US federal rule essentially precluding state criminal defendants from raising an issue in a federal appeal, in this context that they had not been notified of their right to consular assistance, that had not been raised in state courts also breached Article 36 of that Convention.²³ The first judgment (LaGrand) left the choice of means for review and reconsideration of convictions where faced with an alleged Article 36 violation to the US, but the second (Avena) made it clear that the review and reconsideration needed to be conducted by the US courts.²⁴ In sum, both the acknowledgement of treaty-created individual rights and the attempt to speak directly to the role of domestic courts with respect to those rights were novel contributions from the ICJ; however, they arose in the context of a single specific treaty provision which expressly referred to rights and concerned cases involving the death penalty and, accordingly, caution has rightly been emphasized in reading the cases too broadly.²⁵

2.3 Pronouncements of other international courts and supervisory bodies

This section explores pronouncements from other international courts and supervisory bodies as to the legal effects of treaties. The sample is limited to the pronouncements of a range of regional human rights courts and human rights treaty supervisory organs on the assumption that, as they involve the very treaties that have the protection of the individual as their leitmotif, Danzig-type conclusions might have been forthcoming. In addition, this section addresses the paradigm-shifting approach evinced by the manner in which the ECJ interprets the treaties of which it is the authoritative interpreter.

2.3.1 Examples from the sphere of human rights

Regional human rights courts

When we turn to the most prominent of regional human rights instruments, the 1950 ECHR, we find that it provides no express stipulation as to how its substantive obligations are to be discharged. The presence, however, of two provisions has led to much controversy: the first being its Article 1 which provided that ‘The high Contracting Parties shall secure to everyone within their jurisdiction the rights and freedoms defined in Section I of the Convention …’; and, the second, its Article 13 which provides that ‘Everyone whose rights and freedoms as set out in this Convention are violated shall have an effective remedy before a national authority …’; These two provisions, as well as the precision of the ECHR articles and to an extent its travaux préparatoires, led numerous scholars to argue, some invoking the Danzig Opinion in support,²⁶ that there was an international obligation to make the Treaty part of domestic law enforceable before the domestic courts; whilst others strongly contested this reading and emphasized the freedom of the parties to choose how they are to give effect to their obligations.²⁷ As the ECHR was endowed with a judicial organ, there was a body that could resolve the controversy as to the obligations undertaken. In 1976 the European Court of Human Rights (ECtHR) held that ‘neither Article 13 … nor the Convention in general lays down for the Contracting States any given manner for ensuring within their internal law the effective implementation of any of the provisions of the Convention.’²⁸ The Court has since repeated on several occasions that there is no obligation to incorporate the ECHR into domestic law and that Article 13 does not go as far as to guarantee a remedy allowing a contracting State’s laws to be challenged before a national authority on the ground of being contrary to the ECHR.²⁹ Leading scholars, including a former president of the Court, note that this remains the prevailing view.³⁰

The 1969 ACHR is also endowed with a judicial body, modelled on its European counterpart, which is in a position to determine whether the convention needs to be directly applied by domestic courts. The Inter-American Court of Human Rights (IACtHR) has not had to address this issue head on. There has, however, been some controversy in the context of interpreting a 1986 Advisory Opinion.³¹ Scholars on one side, including one of the judges sitting on that very case, consider the decision to establish the direct applicability of a particular ACHR provision as a matter of international law.³² Notwithstanding that only one provision was at issue, they suggest that many ACHR provisions are thus directly applicable as a matter of international law.³³ By contrast, a former judge who also sat in the case suggests that the Court did not go as far but that it did not reject the proposition that the Convention or some of its provisions were directly applicable as a matter of international law and that it was free in the future to so conclude.³⁴ The Court has not had to address this issue again, but it did hand down a judgment in the highly controversial terrain of amnesty laws where it appeared to read the Convention as imposing an obligation on domestic courts not to give effect to domestic law inconsistent with the ACHR.³⁵

UN committees

The core international human rights instruments adopted within the UN framework establish committees of independent experts that monitor implementation of their provisions. There are currently seven such committees. Amongst other things, they publish ‘general comments’ which are interpretations of the provisions of the relevant treaty. Although such general comments are non-binding,³⁶ they are instructive. The two most well-known committees (the Human Rights Committee (HRC) and the Committee on Economic, Social and Cultural Rights (CESCR)) are assigned the task of monitoring State compliance with, respectively, the ICCPR and the ICESCR.

With respect to the CESCR, its general comment of 1998 on the domestic application of the Covenant initially gave the impression that it might be about to reach a Danzig-type conclusion when it asserted that ‘legally binding international human rights standards should operate directly and immediately within the domestic legal system of each State party, thereby enabling individuals to seek enforcement of their rights before national courts and tribunals.’³⁷ That it was not about to pursue a Danzig-like path was then made crystal clear when it proceeded in the following paragraph to acknowledge that the Covenant itself does not stipulate the specific means by which it is to be implemented domestically nor is there any ‘provision obligating its comprehensive incorporation or requiring it to be accorded any type of status in national law’.

Turning to the HRC, its general comment on implementation at the national level of 1981 seemed to make clear that States are free to choose how they implement their obligations.³⁸ Nonetheless, in 2001 one author was to assert, drawing on the Danzig Opinion, that ‘The object of the ICCPR is “to create a special legal regime” governing the relations between individuals and States parties which requires immediate resort to its provisions.’³⁹ The author amassed evidence of recent practice of the HRC in support of the proposition that the ‘States parties need to ensure that the Covenant itself can be applied directly by domestic courts’ and that it ‘needs its own formal place in the domestic legal system so that the Covenant provisions themselves become enforceable by domestic courts.’⁴⁰ But that no such sweeping conclusion would be reached was made plain in its general comment of 2004 where the HRC affirmed that the Covenant does not require that it be ‘directly applicable in the courts, by incorporation of the Covenant into national law’.⁴¹

2.3.2 The European Court of Justice and maximalist treaty enforcement

The notable exception of a judicial body that adopts a fundamentally different approach to the obligations that flow from the treaty that it is charged to interpret is the ECJ. This is a story so well told that only a few of the more salient fundamentals need to be outlined here.⁴² The starting point for what has come to be known as the constitutionalization of European law⁴³ are two seminal judgments delivered some 13 months apart in the early 1960s, where the ECJ outlined the two central planks of the then Community legal order: the principles of direct effect and supremacy.

The direct effect principle was enunciated in the Van Gend en Loos judgment which saw the Court looking to the spirit, general scheme, and the wording of the then EEC Treaty provisions to determine whether an individual could lay claim to individual rights which the national courts must protect.⁴⁴ The objective of the Treaty being to establish a common market of direct concern to interested parties was held to imply that it was more than an agreement merely creating obligations between the Contracting States. Various factors were invoked as confirmation of this proposition: the preamble’s reference to peoples; the establishment of institutions endowed with sovereign rights affecting citizens; the role of nationals in the functioning of the Community via the European Parliament and the Economic and Social Committee; and the preliminary reference procedure which confirmed that EU law could be invoked before domestic courts. The famed conclusion that followed was that EU nationals were held to be subjects of this new legal order which, independently of Member State legislation, is also intended to confer rights upon them. And in the face of contrary submissions from the three intervening Member States, and the Advocate General, the Court held that the Treaty provision at issue produced direct effects and created individual rights which national courts must protect.

This judgment constituted a radical point of departure from that of traditional international law which, as we have seen, starts from the proposition that the domestic legal order determines the legal effect that treaties have therein. The international lawyer might well have been surprised, in light of the Danzig Opinion, at the largely non-existent role played by the intention of the parties,⁴⁵ which is perhaps just as well for most commentators struggle to find such intention in the Treaty of Rome.⁴⁶ Admittedly, there have long been attempts to draw parallels with the Danzig Opinion.⁴⁷ But this is unconvincing for the ECJ was expressly purporting to tell the domestic courts that their obligation under the Treaty was to apply the relevant Treaty provisions. One should not lose sight of the fact that in Danzig the PCIJ referred to the object of the Treaty being the adoption by the parties of definite rules creating rights that would be enforceable in the national courts, whilst here the ECJ was asserting that the Treaty itself created the rights and required no adoption of domestic rules for them to be enforceable in the domestic courts.⁴⁸

Any lingering doubt as to whether the ECJ was indeed claiming that EU law itself determines the effect it has in the domestic legal order was dispensed with in the Costa judgment the following year when it asserted that, unlike ordinary international treaties, the EEC Treaty had created its own legal system which had become an integral part of the Member States’ legal systems and which their courts were bound to apply.⁴⁹ The distinction with respect to the basic premise of international law in terms of the relationship between the international and domestic legal systems could not have been articulated any more starkly.

The Costa judgment is, however, best known for its enunciation of the supremacy principle, namely that because of the special and original nature of Community law it cannot be overridden by domestic legal provisions. The detailed reasoning need not be repeated here,⁵⁰ it is important simply to underline the obvious contrast with respect to international law. Here the ECJ was purporting to tell domestic courts that they were to give EU law primacy in the domestic legal arena and that this requirement flowed from the very nature of Community law.⁵¹ General international law certainly states no rule to the effect that domestic courts are to give effect to international law notwithstanding contrary domestic law.

Conceptually, the bold assertion of the doctrines of direct effect and supremacy represented a veritable paradigm shift: for the first time we had a judicial organ created by treaty asserting that this treaty obliged domestic courts to treat its provisions as the superior law of the land. The developments that have taken place since have been no less striking and have further accentuated the divergence between EU law and international law. The magnitude has been of such nature that over time the language of constitutionalism, fuelled by pronouncements of the ECJ,⁵² has come to be employed in order to capture the richness of these developments.⁵³ The supremacy doctrine was further teased out such that primacy was to obtain, as far as the ECJ was concerned,⁵⁴ over the Constitution itself.⁵⁵ And the criteria for direct effect, that the relevant provision be clear, unconditional, and not require any further implementing measures, proved not to be a great constraint as, to give but two of the better known examples, Treaty provisions were held directly effective even where further implementation by EU legislative organs was envisaged,⁵⁶ or where a principle was at stake that left important criteria undefined.⁵⁷

The direct effect doctrine was extended to EU legislative measures,⁵⁸ which proved especially controversial with respect to unimplemented Directives given that they are addressed to the Member States and the need for domestic implementation is expressly envisaged (Art 288 TFEU). Whilst the direct effect of Directives was ruled out in the context of the horizontal relationship between individuals,⁵⁹ numerous judicial innovations have arisen to mitigate this limitation,⁶⁰ of which the most controversial was State liability in damages for breach of EU law.⁶¹

Crucially, the very doctrine of direct effect has undergone, and continues to undergo, evolution. Traditionally, it was equated with the creation of individual rights,⁶² but gradually it became clear that direct effect was by no means confined to provisions that create individual rights.⁶³ That is, unless we resort to the proposition that the right accorded is simply the right of the individual to rely on a particular provision before domestic courts which would, on most accounts, encapsulate all conceivable manners in which EU law can be employed in domestic courts. The ECJ has certainly lacked consistency in how it employs the language of rights in this context. Accordingly, the doctrine of direct effect which has mutated over time to include legal effects that do not strictly involve individual rights has given rise to ever-increasing commentary as the scholarly community, as well as the Court itself, have struggled to provide an analytical framework that captures the complex jurisprudence.⁶⁴

One distinction, considered to be reflected in the case law, is that between narrow direct effect, understood as the capacity of a provision to confer individual rights enforceable before national courts, and broad direct effect, understood as the capacity of a provision to be invoked before a national court.⁶⁵ Others have largely avoided conceptualization in terms of direct effect preferring instead to conceptualize matters in terms of the different ways in which EU law can be invoked and articulating the hurdles that need to be satisfied for such effects.⁶⁶ Another scholar called for abandoning the doctrine and for Community law to be applied in the domestic legal order without the need for a preliminary inquiry into whether it meets the traditional criteria for direct effect.⁶⁷

There has also been a growing focus upon whether the supremacy principle can be divorced from direct effect, such that it is possible for individuals to rely on primacy to disapply contrary domestic law even absent direct effect. The pedigree of this debate appears to lie in French academic thinking where a distinction has long been proposed between ‘invocabilité d’exclusion’ and ‘invocabilité de substitution’.⁶⁸ The former referring to the setting aside of domestic law that conflicts with Community law based on the supremacy principle without the direct effect criteria needing to be surmounted; the latter referring to the application of the Community rule instead of the conflicting national rule and requiring satisfaction of the direct effect criteria.⁶⁹ Strong support for the essence of this exclusion-substitution distinction was advanced by a member of the ECJ in a co-authored piece which sought to build a general theory of the invocability of the broader sphere of EU law around the primacy principle. On this account, the conventional direct effect criteria of clarity, precision, and unconditionality need to be met where the issue is one of enforcing rights, which would not otherwise exist in the domestic legal order, but not where the issue is one of setting aside incompatible domestic law.⁷⁰

It is clear that the doctrine of direct effect and the broader issue of the invocability of EU law remains shrouded in complexity and, with the judicial stance still evolving, the academic debate is sure to continue unabated. What bears emphasizing is that there has been a powerful current in both the judicial practice of the ECJ and academic thinking that sought to ensure the greatest possible domestic effectiveness for Community—and even pre-Lisbon Union⁷¹—law.⁷² This overriding concern with ensuring the greatest possible effectiveness of EU law in the domestic legal arena—what we can also label a maximalist approach to treaty enforcement—has been a characteristic trait of the jurisprudence with textual niceties rarely standing in the way of this objective. This would account for the core doctrines of direct effect and supremacy and much further innovation by the Court too. Indeed, the case law pertaining to remedies in national law for the enforcement of EU law is replete with references to the mantra of ensuring the full effectiveness of EU law, as EU law so interpreted has come to play an ever more intrusive role in national remedial and procedural law.⁷³ That on occasion the Court has appeared to show restraint, where an unrelenting focus on domestic or maximalist effectiveness would have suggested a different path, does little to dispel the more general trend.⁷⁴

3. Domestic Legal Orders and the Legal Effects of Treaties

Whilst the preceding section explored the general requirements imposed by international law with respect to the legal effects of treaties in the domestic legal arena and the pronouncements of several international courts and supervisory organs, this section looks at the other side of the legal effects of treaties coin, namely the different domestic approaches to their internal legal effect. The legal effect of treaties in the domestic legal order is a domestic constitutional question of immense and growing significance and in a world of over 190 States there is inevitably great variation. It is submitted, however, that we can draw two core distinctions in approach: constitutional systems that automatically incorporate at least certain categories of treaty into the domestic legal order and those that do not. This basic dichotomy will be further elucidated through a brief overview of the approach in the EU’s founding Member States and the first batch of entrants. The approach of the founding Member States has the greatest capacity to shed light on what the drafters may have intended with the relevant provisions of the Treaty of Rome concerning the legal effects of international agreements in the EU legal order, which will be considered in Chapter II. The first batch of entrants represented a constitutional approach falling on the opposite side of the twofold dichotomy to that of the founding Member States. This is also significant because the foundational jurisprudence of the ECJ pertaining to the legal effects of international agreements developed at a time when these countries had acceded; the Court was thus composed of judges steeped in these distinct domestic constitutional traditions and faced with submissions from their governments on these very issues. By elucidating the diverging approaches in this fashion, the chapter that follows is able to articulate more clearly the constitutional ramifications for domestic legal orders of the foundational jurisprudence of the ECJ pertaining to the constitutional status and legal effects of EU Agreements.

The terminology of automatic treaty incorporation refers to a domestic constitutional approach to treaties that in practice operates to ensure that treaties, or certain defined categories of treaty, become automatically incorporated into the domestic legal order. By incorporation what is meant here is that the treaty is considered to become a binding part of domestic law. The adjective ‘automatic’ is intended to capture the fact that this aforementioned status is usually acquired upon the entry into force of the treaty for the relevant State. So defined, this simple categorization of automatic treaty incorporation can accommodate within its remit a great deal of sub-variation. The fact that the treaty becomes part of domestic law, or a variant of such language, can be expressly employed in the Constitution itself;⁷⁵ or it can effectively be read into a less explicit constitutional provision by the courts;⁷⁶ or the Constitution itself can be silent with the courts nonetheless concluding that treaties, or certain categories of treaty,⁷⁷ do indeed become part of domestic law.⁷⁸

Such automatic status can, however, be subject to the requisite domestic constitutional procedures for expressing consent to be bound to a treaty having been satisfied⁷⁹ and/or that the treaty has been published,⁸⁰ or alternatively certain legal effects of a treaty in the judicial arena can only be produced where these requirements have been satisfied.⁸¹ Crucially, however, the practice is usually for such domestic requirements to be satisfied prior to entry into force of the treaty for the State concerned so that upon its entry into force it is considered to become part of the domestic legal order.⁸²

The relevant domestic constitutional procedures can include a constitutionally enshrined, or judicially mandated, requirement that parliamentary consent be given to at least certain treaties,⁸³ and this consent may or may not need to be given in the form of a legislative measure.⁸⁴ Where such measures are required, they can simply authorize ratification or approval of the relevant treaty,⁸⁵ though in some legal orders the practice is for such measures to contain further wording to the effect that the treaty is to be given effect domestically or implemented or some variation thereof.⁸⁶

In terms of the hierarchical status of automatically incorporated treaties, there is considerable variation. The Constitution itself can seek to accord treaties a certain hierarchical standing by providing, for example, that they are superior to (or have precedence over⁸⁷) statutes,⁸⁸ or that they are the supreme law of the land or nation or union,⁸⁹ or some similarly worded variant,⁹⁰ or with less explicit phrasing such as that they are ‘to be faithfully observed’.⁹¹ But even with express constitutionally enshrined language there can still be a crucial role for the courts in deciding whether they are superior to later-in-time statutes,⁹² and potentially even the Constitution and constitutional values.⁹³

Where the Constitution itself is silent as to hierarchy, the issue is left to the courts. In some legal orders they have accorded treaties the same status as that of legislation, which can be of varying rank,⁹⁴ authorizing approval or ratification of the treaty;⁹⁵ in others, the treaty is accorded superior status to ordinary legislation even where it is later in time⁹⁶ and can potentially, albeit this appears extremely rare, even be superior to the Constitution.⁹⁷ Finally, it is important to note that some constitutional systems that automatically incorporate treaties nonetheless allow for challenges to the constitutional validity internally of ratified treaties.⁹⁸

Having briefly defined automatic treaty incorporation and noted some of the extant variations in this respect, we can now elucidate in slightly more detail the automatic treaty incorporation model in the EU’s founding Member States.