OPINION OF ADVOCATE GENERAL

SAUGMANDSGAARD ØE

delivered on 5 June 2018 ( 1 )

Case C‑234/17

XC,

YB,

ZA

in the presence of the

Principal Public Prosecutor

(Request for a preliminary ruling from the Oberster Gerichtshof (Supreme Court, Austria))

(Reference for a preliminary ruling — Principles of EU law — Procedural autonomy — Principles of effectiveness and equivalence — Legal remedy allowing for criminal proceedings closed by a decision having the force of res judicata to be reheard in the event of an infringement of the ECHR — Obligation to extend the scope of that remedy to include infringements of EU law — No such obligation — Article 50 of the Charter of Fundamental Rights of the European Union — Article 54 of the Convention implementing the Schengen Agreement — Principle of ne bis in idem)

I. Introduction

1. By decision of 23 January 2017, the Oberster Gerichtshof (Supreme Court, Austria) submitted a request to the Court for a preliminary ruling on the interpretation of EU law and, in particular, the principles of equivalence and effectiveness.

2. XC, YB and ZA (‘the parties concerned’) are the subject of proceedings in connection with suspected tax evasion and other offences in Switzerland. Pursuant to Article 50(1) of the Convention implementing the Schengen Agreement of 14 June 1985 between the Governments of the States of the Benelux Economic Union, the Federal Republic of Germany and the French Republic on the gradual abolition of checks at their common borders signed in Schengen (Luxembourg) on 19 June 1990, which entered into force on 26 March 1995 ( 2 ) (‘the CISA’), the Staatsanwaltschaft (Public Prosecutor’s Office) for the Canton of St Gallen (Switzerland) submitted several requests for the grant of mutual legal assistance to the Staatsanwaltschaft Feldkirch (Public Prosecutor’s Office, Feldkirch) (Austria) in the form of the questioning of the parties concerned, as defendants.

3. Following the criminal proceedings in Austria, the parties concerned submitted an application before the referring court for a rehearing of criminal proceedings closed by means of a decision with the force of res judicata in the event of an infringement of the Convention for the Protection of Human Rights and Fundamental Freedoms, signed in Rome on 4 November 1950, or one of the protocols thereto (‘ECHR’). That remedy was introduced into Austrian law to allow implementation of judgments of the European Court of Human Rights (‘ECtHR’) establishing an infringement of the ECHR.

4. By their action, the parties concerned alleged, inter alia, an infringement of the ne bis in idem principle enshrined in Article 50 of the Charter of Fundamental Rights of the European Union (‘the Charter’) and Article 54 of the CISA. By its question, the referring court asks, in essence, whether EU law and, in particular, the principles of equivalence and effectiveness, must be interpreted as meaning that the national court is required to assess, in the context of such an action, whether there has been an infringement of EU law — in particular an alleged violation of the fundamental right enshrined in Article 50 of the Charter and Article 54 of the CISA — even though national law provides for such a review only with respect to alleged infringements of the ECHR.

5. I propose that the Court should answer that question in the negative owing to the existence of a ‘constitutional framework’ ( 3 ) established by the Court which ensures the effectiveness of EU law even before national decisions have acquired the force of res judicata and which has no equivalent so far as concerns the ECHR.

II. Legal context

A. EU law

6. The CISA was concluded with a view to ensuring the application of the Agreement of 14 June 1985 between the Governments of the States of the Benelux Economic Union, the Federal Republic of Germany and the French Republic on the gradual abolition of checks at their common borders signed in Schengen. ( 4 )

7. Article 50(1) of the CISA, set out in Title III, Chapter 2, which is entitled ‘Mutual assistance in criminal matters’, provides: ‘The Contracting Parties undertake to afford each other, in accordance with the Convention and the Treaty referred to in Article 48, mutual assistance as regards infringements of their laws and regulations on excise duties, value added tax [VAT] and customs duties. …’

8. Article 54 of the CISA, set out in Title III, Chapter 3, which is entitled ‘Application of the ne bis in idem principle’, provides: ‘A person whose trial has been finally disposed of in one Contracting Party may not be prosecuted in another Contracting Party for the same acts provided that, if a penalty has been imposed, it has been enforced, is actually in the process of being enforced or can no longer be enforced under the laws of the sentencing Contracting Party.’

B. Austrian law

9. On 1 March 1997, Paragraph 363a was incorporated into the Strafprozessordnung (Austrian Code of Criminal Procedure) (‘the Code of Criminal Procedure). That provision provides: ‘1. Where a judgment of the [ECtHR] finds that the [ECHR] has been violated by a decision or order of a criminal court, the case shall, on application, be reheard, in so far as it cannot be ruled out that the violation might have affected the substance of a decision under criminal law in a manner detrimental to the person concerned. 2. All applications for a rehearing shall be adjudicated upon by the Oberster Gerichtshof. The application may be made by the person affected by the violation found or by the Principal Public Prosecutor … The application shall be lodged with the Oberster Gerichtshof. The person concerned shall be given an opportunity to comment on an application made by the Principal Public Prosecutor; the Principal Public Prosecutor shall be given an opportunity to comment on an application made by the person concerned. …’

III. The dispute in the main proceedings

10. The Public Prosecutor’s Office for the Canton of St Gallen (Switzerland) conducted a criminal investigation in respect of XC, YB and others in connection with suspected tax evasion, within the meaning of Article 96(1)(b) of the Swiss Law on VAT (Mehrwertsteuergesetz), and other offences. Those individuals were alleged to have obtained tax refunds to which they were not entitled totalling 835374,17 Swiss francs (CHF) (approximately EUR 698327,41) by submitting incorrect returns to the Swiss tax authorities.

11. In that investigation, the Public Prosecutor’s Office for the Canton of St Gallen submitted a request for the grant of mutual legal assistance to the Public Prosecutor’s Office, Feldkirch (Austria).

12. By order of 15 March 2013, the Oberlandesgericht Innsbruck (Higher Regional Court, Innsbruck), acting in its appellate jurisdiction, following objections and an appeal, held the request for the grant of mutual legal assistance, in the form of the questioning of YB, as defendant, to the Kantonale Untersuchungsamt (Cantonal Investigation Office, Switzerland) to be permissible and dismissed the pleas raised by the Public Prosecutor’s Office, Heilbronn (Germany), and the Fürstliche Landgericht (Princely Court of Justice, Liechtenstein) on the basis of Article 54 of the CISA and the termination of proceedings in 2011 and 2012. In so doing, the Oberlandesgericht drew attention, inter alia, to the charge relating to exports of goods and VAT refunds in the amount of CHF 835374,17 (approximately EUR 698327,41).

13. That decision was the subject of an application for a rehearing which XC and YB made to the referring court. By order of 17 September 2013, that court set aside the orders of the Landesgericht Feldkirch (Regional Court, Feldkirch, Austria) of 31 December 2012 and the Oberlandesgericht Innsbruck (Higher Regional Court, Innsbruck) of 15 March 2013, in so far as they did not relate to the request for mutual legal assistance in connection with the suspected commission of criminal offences detrimental to the Swiss Federal Tax Administration. To the extent that those orders were set aside, the request for the grant of mutual legal assistance was refused. So far as concerns that part of the request for mutual legal assistance unaffected by the setting-aside of those orders, the referring court stated, in the grounds of its decision, that, ‘the request for questioning in connection with the suspected commission of offences detrimental to the Swiss Federal Tax Administration, which is not challenged by the application for a rehearing, will fall to be executed by the Public Prosecutor’s Office’.

14. So far as concerns the part of the request in connection with the suspected commission of offences detrimental to the Swiss Federal Tax Administration, the Public Prosecutor’s Office, Feldkirch, continued the mutual legal assistance proceedings. In that context, the Public Prosecutor’s Office for the Canton of St Gallen tasked it to question other individuals in this regard. The most recent request concerned, inter alia, ZA, as defendant. XC and YB raised objections which were rejected by the Landesgericht Feldkirch (Regional Court, Feldkirch) on the ground that the matter was res judicata. Appeals brought against other orders of the court were unsuccessful.

15. By order of 9 October 2015, the Oberlandesgericht Innsbruck (Higher Regional Court, Innsbruck) dismissed the appeals brought by the parties concerned against the order of the Landesgericht Feldkirch (Regional Court, Feldkirch) of 13 August 2015 and, in the grounds of that order, stated that the request for mutual legal assistance of 23 April 2015 would also be limited to the suspected commission of offences detrimental to the Swiss tax authorites. That court found nothing to indicate that the questioning of ZA might constitute an infringement of Article 54 of the CISA.

16. In making its order of 9 October 2015, the Oberlandesgericht Innsbruck (Higher Regional Court, Innsbruck) adjudicated at second and final instance, in accordance with the Code of Criminal Procedure. That decision has therefore acquired the force of res judicata.

17. The application for a rehearing which the parties concerned brought before the referring court on 18 April 2016 is directed against that order. The parties concerned submit that the grant of mutual legal assistance to the Public Prosecutor’s Office for the Canton of St Gallen constitutes an infringement of Article 6 ECHR, Article 4 of Protocol 7 to the ECHR, Article 50 of the Charter and Article 54 of the CISA. They claim primarily that the referring court should rehear the criminal proceedings and declare the mutual legal assistance inadmissible.

IV. The question referred for a preliminary ruling

18. The referring court notes that the ECHR has constitutional status in Austria. It observes that the ECtHR may not deal with an allegation that the ECHR has been infringed until after all domestic remedies have been exhausted. Consequently, in order to implement judgments of the ECtHR finding that a final decision delivered by a criminal court infringes the ECHR, Paragraph 363a of the Code of Criminal Procedure allows for the submission of an application for the criminal proceedings to be reheard.

19. In addition, the referring court held, in a leading judgment of 1 August 2007, that the rehearing of a criminal case pursuant to that provision is not necessarily contingent upon the existence of a judgment of the ECtHR finding there to have been an infringement of the ECHR. Accordingly, an application for a rehearing may also be granted where the referring court itself establishes that the ECHR has been infringed by a decision or order of a lower criminal court.

20. Consequently, it is possible, on the basis of one of the provisions governing fundamental rights in Austrian law, to pursue a claim alleging that the ECHR has been infringed in the course of an Austrian criminal case directly before the referring court by making an application under Paragraph 363a of the Code of Criminal Procedure, even in the absence of a decision of the ECtHR. Since that judgment of the Oberster Gerichtshof was delivered, increasing use has been made of that remedy.

21. It is in that context that the referring court seeks to ascertain whether there is an obligation arising from the principles of equivalence and effectiveness, as interpreted by the Court, requiring it to extend the scope of the procedure allowing for criminal proceedings to be reheard so as to include alleged infringements of the Charter or other provisions of EU law.

22. In those circumstances, the Oberster Gerichtshof (Supreme Court) decided to stay the proceedings and to refer the following question to the Court of Justice for a preliminary ruling: ‘Is EU law, in particular Article 4(3) TEU in conjunction with the principles of equivalence and effectiveness inferred from it, to be interpreted as requiring the [national court], upon application by the person concerned, to review a final decision delivered by a criminal court with respect to an alleged infringement of EU law (in this case, Article 50 of the [Charter] and Article 54 of the [CISA]), where national law … provides for such a review only with respect to an alleged violation of the [ECHR]?’

V. Procedure before the Court

23. The reference for a preliminary ruling was lodged at the Court Registry on 4 May 2017.

24. Written observations were submitted by the Austrian and Hungarian Governments, as well as the European Commission.

25. At the hearing, held on 20 March 2018, the Austrian and Hungarian Governments and the Commission presented oral argument.

VI. Analysis

26. By its question, the referring court asks whether EU law and, in particular, the principles of equivalence and effectiveness, must be interpreted as requiring the national court to extend the scope of a legal remedy provided for by a national provision allowing for criminal proceedings closed by means of a decision with the force of res judicata to be reheard in the event of an infringement of the ECHR, to include infringements of EU law, in particular infringements of the fundamental right guaranteed by Article 50 of the Charter and Article 54 of the CISA.

27. As a preliminary point, I note that Article 50 of the Charter and Article 54 of the CISA concern the fundamental right not to be tried or punished twice in criminal proceedings for the same criminal offence, the ne bis in idem principle.

28. All parties that have submitted observations to the Court take the view that the answer to the question referred should be in the negative. That is also my opinion, for the reasons set out below.

29. It is settled case-law that, in the absence of EU legislation in this area, detailed procedural rules governing actions for safeguarding the rights which taxpayers derive from EU law, including the rules for giving effect to the principle of res judicata, are a matter for the domestic legal order of the Member States by virtue of the principle that Member States enjoy procedural autonomy. However, such procedural rules must not be less favourable than those governing similar domestic situations (principle of equivalence) and must not be framed in such a way as to make it in practice impossible or excessively difficult to exercise the rights conferred by EU law (principle of effectiveness). ( 5 )

30. In the present case, it is common ground that there is no EU legislation governing a legal remedy such as that which gave rise to the dispute in the main proceedings, that is to say a legal remedy which makes it possible for the parties concerned to claim that a decision with the force of res judicata delivered by a criminal court infringes a fundamental right — in this case, a fundamental right guaranteed by the ECHR — and, where appropriate, for the proceedings to be reheard.

31. Consequently, and in accordance with the aforementioned case-law, it is necessary to examine whether the provision of such a remedy with respect to infringements of the ECHR, without extending its scope to include infringements of EU law, undermines the principles of equivalence and effectiveness, as interpreted by the Court. I will examine those two aspects separately in Sections B and C below.

32. At the outset, I will set out the reasons why I consider that the plea of inadmissibility raised by the Austrian Government should be rejected (Section A).

A. Admissibility of the request for a preliminary ruling

33. The Austrian Government raised a plea of inadmissibility against the present reference for a preliminary rule. The Austrian Government takes the view that it is doubtful whether the circumstances of the main proceedings fall within the scope of EU law, in so far as Paragraph 363a of the Code of Criminal Procedure provides for a legal remedy in the event of an infringement of the ECHR, not an infringement of EU law.

34. It is settled case-law that questions on the interpretation of EU law referred by a national court in the factual and legislative context which that court is responsible for defining, the accuracy of which is not a matter for the Court to determine, enjoy a presumption of relevance. The Court may refuse to rule on a question referred by a national court only where it is quite obvious that the interpretation of EU law that is sought bears no relation to the actual facts of the main action or its purpose, where the problem is hypothetical, or where the Court does not have before it the factual or legal material necessary to give a useful answer to the questions submitted to it. ( 6 )

35. So far as concerns the first argument put forward by the Austrian Government, I would point out that the CISA was originally an international agreement concluded outside the framework of the European Union. However, the Treaty of Amsterdam integrated the Schengen acquis into the framework of the European Union. ( 7 ) As was rightly pointed out by Advocate General Kokott in the case of E, ( 8 ) the CISA has therefore become an integral part of EU law applicable by Member States participating in the Schengen area.

36. Consequently, where the authorities of a Member State uphold a request for the grant of mutual legal assistance on the basis of the CISA, as in circumstances such as those in the main proceedings, it should be noted that they are implementing EU law within the meaning of Article 51(1) of the Charter. That interpretation is supported by the judgment in M, in which the Court held that Article 54 of the CISA must be interpreted in the light of Article 50 of the Charter, ( 9 ) and by the judgment in Spasic, in which the Court examined the validity of Article 54 of the CISA in the light of Article 50 of the Charter. ( 10 )

37. In addition, the Austrian Government argued that the referring court has not set out the precise reasons which prompted it to raise the question of the interpretation of EU law and to consider it necessary to refer a question to the Court for a preliminary ruling. With regard to that second argument, I consider that the referring court has made it clear that it has doubts as to the existence of an obligation to extend the scope of the legal remedy provided for in Paragraph 363a of the Code of Criminal Procedure to include infringements of EU law, and in particular infringements of fundamental rights guaranteed by the Charter or by the CISA.

38. I would add that that question is significant to the outcome of the case in the main proceedings, since the Charter may, pursuant to Article 53 thereof, give greater protection than that provided for by the ECHR. That is indeed the case with regard to the ne bis in idem principle relied on in the main proceedings. As noted in the explanations relating to the Charter of Fundamental Rights, ( 11 ) although the scope of the ne bis in idem principle set out in Article 4(1) of Protocol No 7 to the ECHR is limited to the territory of each State considered separately, ( 12 ) Article 50 of the Charter extends it to cover the territory of the Union, regarded as one entity. ( 13 ) Following the example of Article 50 of the Charter, the territorial scope of Article 54 of the CISA covers the territory of all the Member States participating in the Schengen area, regarded as one entity.

39. In the light of the foregoing, I consider that there is little question that the order for reference is admissible.

B. No infringement of the principle of effectiveness of EU law

40. In order to assess the existence of an infringement of the principle of effectiveness of EU law, it is necessary to establish whether the impossibility of challenging a final decision delivered by a criminal court with respect to an infringement of EU law, in particular an alleged violation of the fundamental right enshrined in Article 50 of the Charter and Article 54 of the CISA, makes it in practice impossible or excessively difficult to exercise the rights conferred by EU law within the meaning of the case-law referred to in point 29 of this Opinion.

41. In my view, it is apparent from the Court’s case-law that the principle of effectiveness of EU law does not demand, subject to certain exceptions, that the principle of res judicata in respect of national decisions contrary to EU law be called into question, in particular by establishing a specific legal remedy. That case-law is explained by the existence of a constitutional framework established by the Court which guarantees the effectiveness of EU law even before national decisions have acquired the force of res judicata (Section 1).

42. Indeed, the Court has created an exception to the principle of res judicata in respect of national decisions in the event that the individual concerned has not been able to exercise the rights conferred on him by EU law. That exception is not, however, relevant in circumstances such as those in the main proceedings (Section 2).

1. The principle: respect for national decisions which have acquired the force of res judicata

43. With regard to the principle of effectiveness, the Court has consistently held that every case in which the question arises as to whether a national procedural provision makes the application of EU law impossible or excessively difficult must be analysed by reference to the role of that provision in the procedure, its conduct, and its special features, viewed as a whole, before the various national bodies. In that context, it is necessary to take into consideration, where relevant, the principles which lie at the basis of the national legal system, such as the protection of the rights of the defence, the principle of legal certainty and the proper conduct of the proceedings. ( 14 )

44. Nevertheless, the Court has also consistently held that attention should be drawn to the importance, both in the legal order of the European Union and in national legal systems, of the principle of res judicata. In order to ensure both stability of the law and legal relations and the sound administration of justice, it is important that decisions of courts or tribunals which have become definitive after all rights of appeal have been exhausted or after expiry of the time limits provided for in that connection can no longer be called into question. ( 15 )

45. It cannot be denied that there is some tension between the two principles. The impossibility of challenging a final decision delivered by a national court, in respect of which an infringement of EU law has been established, necessarily affects the effectiveness of EU law.

46. However, such an effect does not imply, in itself, an infringement of the principle of effectiveness as interpreted by the Court. Indeed, it is settled case-law that EU law does not always require a national court to disapply domestic rules of procedure conferring the force of res judicata on a judgment, even if to do so would make it possible to remedy a breach of EU law. ( 16 )

47. In particular, the Court has excluded any infringement of the principle of effectiveness of EU law in situations where the principle of res judicata precludes the national court from examining the validity of arbitration awards under Article 101 TFEU ( 17 ) or EU rules relating to unfair terms in consumer contracts. ( 18 ) In the same way, the Court has accepted that the principle of res judicata precludes the national court from examining the validity of decisions on EU rules relating to the international jurisdiction of national courts, ( 19 ) public works contracts ( 20 ) or Article 110 TFUE. ( 21 )

48. Hence, as a general rule, the principle of effectiveness of EU law does not require Member States to call into question the principle of res judicata in respect of national decisions, in particular by establishing a specific legal remedy such as that provided for in Paragraph 363a of the Code of Criminal Procedure in the event of an infringement of the ECHR.

49. In my opinion, that case-law is explained by the existence of a constitutional framework conferring many of the specific features of EU law ( 22 ) and guaranteeing the effectiveness of EU law even before national decisions have acquired the force of res judicata.

50. In the first place, binding provisions of EU law are capable of conferring rights directly on individuals. ( 23 ) That principle of direct effect implies that EU law not only concerns relations between States but also confers rights on individuals which may be asserted before any State authority, in particular any national court.

51. So far as concerns the fundamental right at issue in the main proceedings, the Court recently held, in the judgment in Garlsson Real Estate and Others, ( 24 ) that the ne bis in idem principle provided for in Article 50 of the Charter confers on individuals a directly applicable right.

52. In the second place, the principle of the primacy of EU law requires national courts to give full effect to directly applicable provisions of EU law, if necessary refusing of their own motion to apply any conflicting provision of national legislation, even if adopted subsequently, and it is not necessary for a court to request or await the prior setting aside of such a provision by legislative or other constitutional means. ( 25 )

53. It is apparent from the cumulative effect of the principles of the direct effect and primacy of EU law that any Austrian court seised of the case in the main proceedings is required to remedy any infringement of the ne bis in idem principle guaranteed by Article 50 of the Charter and Article 54 of the CISA. In that regard, the referring court expressly notes that the Code of Criminal Procedure provides individuals with a range of legal means of enforcing in criminal proceedings the exercise of the rights conferred on them by EU law, including the right provided for in Article 50 of the Charter. In addition, it is clear from the description of the facts set out by the referring court that the parties concerned did in fact have the opportunity to bring several actions in the course of the criminal proceedings against them claiming, in particular, the infringement of provisions of EU law such as Article 54 of the CISA. ( 26 )

54. In the third place, it is apparent from the second paragraph of Article 267 TFEU, as interpreted by the Court, that national courts have the widest discretion in referring matters to the Court if they consider that a case pending before them raises questions involving interpretation of provisions of EU law, or consideration of their validity, necessitating a decision on their part. ( 27 ) Accordingly, it is permissible for national courts, before adopting a decision settling the case pending before them, to make a reference to the Court to obtain a binding interpretation on EU law. Under the third paragraph of Article 267 TFEU, that discretion even becomes an obligation — except in cases of ‘acte claire’ ( 28 ) — where any such a question is raised in a case pending before a court or tribunal of a Member State against whose decisions there is no judicial remedy under national law. ( 29 )

55. In my opinion, that constitutional framework guarantees, in principle, the possibility for a normally diligent person to exercise the rights conferred on him by EU law even before being the subject of a decision which has acquired the force of res judicata. Accordingly, that framework guarantees the effectiveness of EU law without the need to establish a legal remedy allowing for national decisions which have acquired the force of res judicata to be challenged.

56. I would add that that constitutional framework is supplemented by the obligation on Member States to establish a legal remedy allowing for the possibility of rendering the State liable for an infringement of EU law owing to a decision of a national court adjudicating at last instance. ( 30 ) Contrary to the three constitutional principles described above, that obligation arises after the national decision has acquired the force of res judicata. The Court held, in that regard, that the principle of res judicata does not preclude recognition of the principle of State liability for the decision of a court adjudicating at last instance. ( 31 )

57. In the light of the foregoing, the impossibility, in circumstances such as those at issue in the main proceedings, of challenging a final decision delivered by a criminal court with respect to an infringement of EU law, in particular an infringement of the fundamental right guaranteed by Article 50 of the Charter and Article 54 of the CISA, does not constitute an infringement of the principle of effectiveness of EU law.

2. The exception: calling into question the principle of res judicata in respect of national decisions where the individual concerned has not been able to exercise the rights conferred on him by EU law

58. I should point out, however, that the Court has established an exception to the principle of res judicata in respect of national decisions, in the event that compliance with that principle would negate the effectiveness of a national procedure in respect of which certain structural features make it in practice impossible or excessively difficult to exercise the rights conferred by EU law.

59. In that regard, the Court has held, in particular, that a national rule which, in tax disputes where a final judgment in a given case concerns a fundamental issue common to other cases, has binding authority as regards that issue is not compatible with the principle of effectiveness. Indeed, a rule of that kind would have the consequence of imposing erga omnes the interpretation adopted in the first decision, in particular so far as it concerns an abusive practice in the field of VAT, with no possibility of rectifying any misinterpretation of EU law. ( 32 )

60. In another case, the Court held that the principle of effectiveness of EU law also precludes the application of a national rule which prevents the national court from drawing all the consequences of a breach of the prohibition on implementation of State aid provided for in the third sentence of Article 108(3) TFEU because of a national judicial decision which has become definitive, and which has found, without examining whether the contracts at issue in the main proceedings constitute State aid, that the contracts remain in force. In the present case, that rule would have prevented monitoring of compliance with the aforementioned prohibition. ( 33 )

61. I would note, however, that a straightforward lack of diligence in the exercise of the rights conferred by EU law is not sufficient to challenge the finality of national decisions. ( 34 ) In other words, calling that principle into question, in order to preserve the effectiveness of EU law, concerns only procedures in respect of which certain structural features make it in practice impossible or excessively difficult to exercise the rights conferred by EU law.

62. In the present case, there is nothing in the documents before the Court to suggest that this would be the case in respect of the procedure at issue in the main proceedings. ( 35 )

63. In the light of the foregoing, I consider that the principle of effectiveness of EU law must be interpreted as meaning that the national court is not required to extend the scope of a legal remedy provided for by a national provision allowing for criminal proceedings closed by means of a decision with the force of res judicata to be reheard in the event of an infringement of the ECHR, so as to include infringements of EU law, in particular infringements of the fundamental right guaranteed by Article 50 of the Charter and Article 54 of the CISA, where the individual concerned has been able to exercise the rights conferred on him by EU law in the course of the criminal proceedings.

C. No infringement of the principle of equivalence

64. In order to respond to the question referred for a preliminary ruling, it is still necessary to determine whether the provision of a legal remedy allowing for criminal proceedings closed by means of a decision with the force of res judicata to be reheard in the event of an infringement of the ECHR, without extending its scope to include infringements of EU law, in particular infringements of the fundamental right guaranteed by Article 50 of the Charter and Article 54 of the CISA, constitutes an infringement of the principle of equivalence.

65. Pursuant to the case-law referred to in point 29 of this Opinion, the principle of equivalence requires that the detailed procedural rules governing actions for safeguarding the rights which taxpayers derive from EU law must not be any less favourable than those governing similar domestic actions.

66. For the reasons set out below, I consider that the principle of equivalence does not require Member States to extend the scope of a legal remedy such as that at issue in the main proceedings to include EU law.

67. In the first place, a claim based on the ECHR does not constitute a ‘similar domestic action’ within the meaning of the aforementioned case-law, in so far as it does not concern the infringement of national law. Regardless of the status granted to the ECHR in the hierarchy of norms by the national legal order, ( 36 ) I consider that the expression ‘national law’ does not include rules which may be amended or withdrawn by institutions of the Member State concerned. In other words, the expression ‘national law’ refers exclusively to rules originating in the domestic legal order of the Member State concerned. It is clear that, like any instrument of national law, the ECHR does not contain such rules.

68. That interpretation is in line with the objective pursued by the principle of equivalence, which is to prevent Member State practices amounting to procedural protectionism and granting privileged status to domestic rules in relation to that granted to EU law. In the judgment in Târşia, the Court held, in that regard, that the principle of equivalence requires equal treatment of claims based on a breach of national law and of similar claims based on a breach of EU law. ( 37 )

69. The granting of privileged status to the ECHR, that is to say a body of international rules, does not constitute discriminatory treatment within the meaning of that case-law. In other words, the status granted to the ECHR is not a relevant comparative reference for the purposes of applying the principle of equivalence. Taking account of that status would turn the principle of equivalence into a ‘most favoured rule’ clause, pursuant to which the most favourable treatment envisaged by a Member State, whether in respect of national or international rules, should automatically be extended to EU law.

70. In the second place, even if a claim based on the ECHR is to be treated in the same way as a domestic action, it should also be borne in mind that there is no infringement of the principle of equivalence in the circumstances of the main proceedings, in so far as a claim based on the ECHR is not ‘similar’ to a claim based on EU law.

71. Indeed, according to settled case-law, the principle of equivalence requires equal treatment of claims based on an infringement of EU law and ‘similar’ domestic actions. ( 38 ) Consequently, that principle cannot be interpreted as requiring a Member State to extend its most favourable rules to all actions brought in a certain area of law ( 39 ) or indeed to those alleging infringements of EU law. ( 40 )

72. According to that case-law, it is necessary to consider whether the actions concerned are similar as regards their purpose, cause of action and essential characteristics, by establishing, where appropriate, whether the rules at issue are similar taking into account the role played by those rules in the procedure as a whole, the conduct of that procedure and any special features of those rules. ( 41 )

73. The claims based, respectively, on the ECHR and on EU law cannot be regarded as similar, in particular taking into account the role played by those rules in the national procedure within the meaning of the aforementioned case-law.

74. As I pointed out above, EU law is characterised by the existence of a constitutional framework requiring Member States to guarantee the effectiveness of EU law even before national decisions have acquired the force of res judicata. ( 42 )

75. By contrast, the admissibility of an action before the ECtHR is subject to all domestic remedies having been exhausted in accordance with Article 35(1) of the ECHR. That requirement necessarily implies that a judgment of the ECtHR finding there to have been an infringement of the ECHR cannot be taken until after a decision is taken by a national court adjudicating at last instance which is presumed to have acquired the force of res judicata. As pointed out by the referring court, it is precisely in order to implement the judgments of the ECtHR that the legal remedy under Paragraph 363a of the Code of Criminal Procedure was introduced.

76. In my opinion, that objective difference between EU law and the ECHR implies that domestic actions based, respectively, on those two bodies of rules and relating to the validity of national decisions which have acquired the force of res judicata, cannot be regarded as similar.

77. Indeed, the effectiveness of judgments delivered by the ECtHR finding an infringement of the ECHR is necessarily dependent on action on the part of the Member State concerned after all domestic remedies have been exhausted, inter alia, by the provision of a legal remedy making it possible to review decisions which have acquired the force of res judicata such as that provided for in Paragraph 363a of the Code of Criminal Procedure.

78. By contrast, the effectiveness of EU law and, in particular, judgments of the Court, does not require the provision of such a remedy, in so far as the constitutional framework consisting of direct effect, primacy of EU law and the preliminary ruling procedure guarantees its effectiveness even before national decisions have acquired the force of res judicata.

79. In that regard, as the Court held in Opinion 2/13, the judicial system of the Union has as its keystone the preliminary ruling procedure, which, by setting up a dialogue between one court and another, specifically between the Court of Justice and the courts and tribunals of the Member States, has the object of securing uniform interpretation of EU law, thereby serving to ensure its consistency, its full effect and its autonomy as well as, ultimately, the particular nature of the law established by the Treaties. ( 43 )

80. I would point out that the entry into force of Protocol No 16 to the ECHR (‘Protocol No 16’) on 1 August 2018, following ratification by the French Republic on 12 April 2018, ( 44 ) is not liable to undermine the lack of similarity. Indeed, on the one hand, the Republic of Austria is not a signatory to the protocol. ( 45 )

81. On the other hand, and in any event, I consider that, even with regard to the States signatories, Protocol No 16 is not liable to increase the effectiveness of the ECHR before national decisions have acquired the force of res judicata to a level comparable to that of EU law.

82. It is true that Protocol No 16 introduces the possibility of requesting the ECtHR to give advisory opinions on questions of principle relating to the interpretation or application of the rights and freedoms defined in the ECHR or the protocols thereto. However, there are three significant differences between that mechanism and the one established by Article 267 TFEU. First, that possibility is limited to the ‘highest courts and tribunals’ of a High Contracting Party pursuant to Article 1 of Protocol No 16. Second, the ECtHR will decide whether to accept those requests in accordance with Article 2 of that protocol. Third, Article 5 of that protocol states that advisory opinions given in that context are not binding.

83. In the light of the foregoing, I consider that domestic actions based, respectively, on EU law and on the ECHR, relating to the validity of national decisions which have acquired the force of res judicata, cannot be regarded as similar. Consequently, there is no obligation under the principle of equivalence to extend the scope of a legal remedy making it possible to review decisions concerning the ECHR which have acquired the force of res judicata, such as that provided for in Paragraph 363a of the Code of Criminal Procedure, so as to include EU law.

84. That lack of similarity is not called into question by the fact that the referring court can itself find there to have been an infringement of the ECHR in the context of proceedings under Paragraph 363a of the Code of Criminal Procedure, without the existence of a judgment of the ECtHR. ( 46 ) Admittedly, that possibility increases the effectiveness of the ECHR by allowing criminal proceedings closed by means of a final decision to be reheard without the individual concerned having to bring the matter before the ECtHR. However, the effectiveness of the ECHR and of judgments of the ECtHR is not guaranteed until national decisions have acquired the force of res judicata, unlike the effectiveness of EU law and, in particular, judgments of the Court of Justice.

85. Having said that, the absence of an obligation to extend the scope of such a remedy to include infringements of EU law does not, in my view, prohibit such an extension. Indeed, it is permissible for Member States to establish, in the exercise of their procedural autonomy, ( 47 ) a remedy allowing national decisions which have acquired the force of res judicata to be challenged in the event of an infringement of EU law.

86. In circumstances such as those at issue in the main proceedings, it is therefore open to the referring court to apply EU law in the context of the remedy provided for in Paragraph 363a of the Code of Criminal Procedure. In that regard, it is apparent from the written and oral observations submitted by the Austrian Government that the referring court found there to be a breach of Article 54 of the CISA in a judgment delivered in the course of those proceedings.

87. Nevertheless, I would point out that the exercise of that discretion does not give rise to an obligation to continue applying EU law in the context of that legal remedy, at least in the light of EU law and, in particular, the principle of equivalence. Indeed, that fact is not such as to affect the argument set out above that claims based, respectively, on EU law and on the ECHR cannot be regarded as similar.

88. In the light of the foregoing, I consider that the principle of equivalence must be interpreted as not requiring a national court to extend the scope of a legal remedy, provided for by a national provision allowing criminal proceedings closed by means of a decision with the force of res judicata to be reheard in the event of an infringement of the ECHR, so as to include infringements of EU law, in particular infringements of the fundamental right guaranteed by Article 50 of the Charter and Article 54 of the CISA.

VII. Conclusion

89. In the light of the foregoing, I propose that the Court should answer the question referred for a preliminary ruling by the Oberster Gerichtshof (Supreme Court, Austria) as follows: EU law and, in particular, the principles of equivalence and effectiveness must be interpreted as not requiring a national court to extend the scope of a legal remedy, provided for by a national provision allowing criminal proceedings closed by means of a decision with the force of res judicata to be reheard in the event of an infringement of the European Convention for the Protection of Human Rights and Fundamental Freedoms or one of the protocols thereto, so as to include infringements of EU law, in particular infringements of the fundamental right guaranteed by Article 50 of the Charter of Fundamental Rights of the European Union and Article 54 of the Convention implementing the Schengen Agreement of 14 June 1985 between the Governments of the States of the Benelux Economic Union, the Federal Republic of Germany and the French Republic on the gradual abolition of checks at their common borders signed in Schengen on 19 June 1990 and entered into force on 26 March 1995, where the individual concerned has been able to exercise the rights conferred on him by EU law in the course of the criminal proceedings.

( 1 ) Original language: French.

( 2 ) OJ 2000 L 239, p. 19.

( 3 ) That expression was used by the Court in Opinion 2/13 (Accession of the European Union to the ECHR) of 18 December 2014 (EU:C:2014:2454, paragraphs 158 and 177).

( 4 ) OJ 2000 L 239, p. 13.

( 5 ) See, in particular, judgments of 16 March 2006, Kapferer (C‑234/04, EU:C:2006:178, paragraphs 21 and 22); of 26 October 2006, Mostaza Claro (C‑168/05, EU:C:2006:675, paragraph 24); of 3 September 2009, Fallimento Olimpiclub (C‑2/08, EU:C:2009:506, paragraph 24); of 6 October 2015, Târşia (C‑69/14, EU:C:2015:662, paragraph 27); and of 18 February 2016, Finanmadrid EFC (C‑49/14, EU:C:2016:98, paragraph 40).

( 6 ) See, in particular, judgments of 7 December 2017, López Pastuzano (C‑636/16, EU:C:2017:949, paragraph 19), and of 23 January 2018, F. Hoffmann-La Roche and Others (C‑179/16, EU:C:2018:25, paragraph 45).

( 7 ) See Protocol No 19 on the Schengen acquis integrated into the framework of the European Union, annexed to the TEU and TFEU.

( 8 ) Opinion of Advocate General Kokott in E (C‑240/17, EU:C:2017:963, point 82).

( 9 ) Judgment of 5 June 2014 (C‑398/12, EU:C:2014:1057, paragraph 35). See also judgment of 29 June 2016, Kossowski (C‑486/14, EU:C:2016:483, paragraph 31).

( 10 ) Judgment of 27 May 2014 (C‑129/14 PPU, EU:C:2014:586, paragraphs 51 to 74).

( 11 ) OJ 2007 C 303, p. 17.

( 12 ) ‘No one shall be liable to be tried or punished again in criminal proceedings under the jurisdiction of the same State for an offence for which he has already been finally acquitted or convicted in accordance with the law and penal procedure of that State’. See, most recently, ECtHR, 20 February 2018, Krombach v. France (CE:ECHR:2018:0220DEC006752114, § 34 to 41).

( 13 ) ‘No one shall be liable to be tried or punished again in criminal proceedings for an offence for which he or she has already been finally acquitted or convicted within the Union in accordance with the law’.

( 14 ) See, in particular, judgments of 3 September 2009, Fallimento Olimpiclub (C‑2/08, EU:C:2009:506, paragraph 27); of 6 October 2009, Asturcom Telecomunicaciones (C‑40/08, EU:C:2009:615, paragraph 39); of 14 June 2012, Banco Español de Crédito (C‑618/10, EU:C:2012:349, paragraph 49); of 6 October 2015, Târşia (C‑69/14, EU:C:2015:662, paragraph 36); of 11 November 2015, Klausner Holz Niedersachsen (C‑505/14, EU:C:2015:742, paragraph 41); and of 18 February 2016, Finanmadrid EFC (C‑49/14, EU:C:2016:98, paragraph 43).

( 15 ) See, in particular, judgments of 30 September 2003, Köbler (C‑224/01, EU:C:2003:513, paragraph 38); of 16 March 2006, Kapferer (C‑234/04, EU:C:2006:178, paragraph 20); of 3 September 2009, Fallimento Olimpiclub (C‑2/08, EU:C:2009:506, paragraph 22); of 6 October 2009, Asturcom Telecomunicaciones (C‑40/08, EU:C:2009:615, paragraphs 35 and 36); of 10 July 2014, Impresa Pizzarotti (C‑213/13, EU:C:2014:2067, paragraph 58); of 6 October 2015, Târşia (C‑69/14, EU:C:2015:662, paragraph 28); and of 11 November 2015, Klausner Holz Niedersachsen (C‑505/14, EU:C:2015:742, paragraph 38).

( 16 ) See, in particular, judgments of 1 June 1999, Eco Swiss (C‑126/97, EU:C:1999:269, paragraph 47); of 16 March 2006, Kapferer (C‑234/04, EU:C:2006:178, paragraph 21); of 3 September 2009, Fallimento Olimpiclub (C‑2/08, EU:C:2009:506, paragraph 23); of 6 October 2009, Asturcom Telecomunicaciones (C‑40/08, EU:C:2009:615, paragraph 37); of 10 July 2014, Impresa Pizzarotti (C‑213/13, EU:C:2014:2067, paragraph 59); of 6 October 2015, Târşia (C‑69/14, EU:C:2015:662, paragraph 29); and of 11 November 2015, Klausner Holz Niedersachsen (C‑505/14, EU:C:2015:742, paragraph 39).

( 17 ) Judgment of 1 June 1999, Eco Swiss (C‑126/97, EU:C:1999:269, paragraphs 43 to 48).

( 18 ) Judgment of 6 October 2009, Asturcom Telecomunicaciones (C‑40/08, EU:C:2009:615, paragraphs 39 to 48).

( 19 ) Judgment of 16 March 2006, Kapferer (C‑234/04, EU:C:2006:178, paragraphs 19 to 24).

( 20 ) Judgment of 10 July 2014, Impresa Pizzarotti (C‑213/13, EU:C:2014:2067, paragraphs 58 to 61).

( 21 ) Judgment of 6 October 2015, Târşia (C‑69/14, EU:C:2015:662, paragraphs 36 to 41).

( 22 ) See, in particular, Opinion 2/13 (Accession of the EU to the ECHR) of 18 December 2014 (EU:C:2014:2454, point 166): ‘as the Court of Justice has noted many times, EU law is characterised by the fact that it stems from an independent source of law, the Treaties, by its primacy over the laws of the Member States … and by the direct effect of a whole series of provisions which are applicable to their nationals and to the Member States themselves …’. See also the judgment of 6 March 2018, Achmea (C-284/16, EU:C:2018:158, paragraph 33).

( 23 ) Regulations, owing to their very nature and their place in the system of sources of EU law, operate to confer rights on individuals which the national courts have a duty to protect (see, in particular, judgments of 14 December 1971, Politi, 43/71, EU:C:1971:122, paragraph 9, and of 17 September 2002, Muñoz et Superior Fruiticola, C‑253/00, EU:C:2002:497, paragraph 27). The provisions of primary law which impose precise and unconditional obligations, not requiring, for their application, any further action on the part of the EU or national authorities, create direct rights in respect of the individuals concerned (see, in particular, judgments of 5 February 1963, van Gend & Loos, 26/62, EU:C:1963:1, p. 24 and 25, and of 20 March 2018, Garlsson Real Estate and Others, C‑537/16, EU:C:2018:193, paragraph 65). Whenever the provisions of a directive appear, so far as their subject matter is concerned, to be unconditional and sufficiently precise, they may be relied upon before the national courts by individuals against the State where the latter has failed to implement the directive in domestic law by the end of the period prescribed or where it has failed to implement the directive correctly (see, in particular, judgments of 4 December 1974, van Duyn, 41/74, EU:C:1974:133, paragraphs 11 to 15, and of 15 January 2014, Association de médiation sociale, C‑176/12, EU:C:2014:2, paragraph 31)).

( 24 ) Judgment of 20 March 2018 (C‑537/16, EU:C:2018:193, paragraphs 64 to 68).

( 25 ) See, in particular, judgments of 15 July 1964, Costa (6/64, EU:C:1964:66, p. 1158 to 1160); of 9 March 1978, Simmenthal (106/77, EU:C:1978:49, paragraphs 21 and 24); of 22 October 1998, IN. CO. GE.’90 and Others (C‑10/97 to C‑22/97, EU:C:1998:498, paragraphs 20 and 21); of 11 September 2014, A (C‑112/13, EU:C:2014:2195, paragraphs 36 and 37); and of 6 March 2018, SEGRO and Horváth (C‑52/16 and C‑113/16, EU:C:2018:157, paragraph 46).

( 26 ) See points 12 to 16 of this Opinion. I note, in that regard, that there is no evidence on the file on the basis of which to suspect an infringement of the fundamental right to effective judicial protection guaranteed by the second paragraph of Article 19(1) TFEU and by Article 47 of the Charter (see judgment of 27 February 2018, Associação Sindical dos Juízes Portugueses, C‑64/16, EU:C:2018:117, paragraphs 34 to 36). Moreover, the referring court has not referred any questions to the Court on this point. So far as this point is relevant, I note that the Court, in particular in the many cases cited in this section, has not interpreted the scope of that fundamental right as entailing the possibility of challenging a final decision delivered by a national court on the basis of an infringement of EU law.

( 27 ) See, in particular, judgments of 11 September 2014, A (C‑112/13, EU:C:2014:2195, paragraph 35) and of 5 April 2016, PFE (C‑689/13, EU:C:2016:199, paragraphs 31 to 36).

( 28 ) See, in particular, judgments of 6 October 1982, Cilfit and Others (283/81, EU:C:1982:335, paragraphs 16 to 21) and of 28 July 2016, Association France Nature Environnement (C‑379/15, EU:C:2016:603, paragraphs 47 to 53).

( 29 ) Failure to comply with that obligation may, in some circumstances, be the subject of infringement proceedings: see, in that regard, the action brought by the Commission in Commission v France (C‑416/17).

( 30 ) See, in particular, judgments of 30 September 2003, Köbler (C‑224/01, EU:C:2003:513, paragraphs 34 to 36), and of 6 October 2015, Târşia (C‑69/14, EU:C:2015:662, paragraph 40).

( 31 ) Judgment of 30 September 2003, Köbler (C‑224/01, EU:C:2003:513, paragraph 40).

( 32 ) Judgment of 3 September 2009, Fallimento Olimpiclub (C‑2/08, EU:C:2009:506, paragraphs 26 to 32).

( 33 ) Judgment of 11 November 2015, Klausner Holz Niedersachsen (C‑505/14, EU:C:2015:742, paragraphs 42 to 46).

( 34 ) In the judgment of 6 October 2009, Asturcom Telecomunicaciones (C‑40/08, EU:C:2009:615, paragraphs 47 and 48), relating to an application for the enforcement of an arbitration award that has become final, the Court held that the principle of effectiveness does not require the court dealing with the case to assess of its own motion whether an arbitration clause is unfair where the consumer concerned has not brought an action for annulment of the arbitration award. By contrast, a court seised of an action for annulment of an arbitration award is required to annul that award where that agreement contains an unfair term, even though the consumer has not pleaded that invalidity in the course of the arbitration proceedings, but only in that of the action for annulment (judgment of 26 October 2006, Mostaza Claro, C‑168/05, EU:C:2006:675, paragraphs 30 to 39). Likewise, the principle of effectiveness permits the court ruling on the enforcement of an order for payment to assess of its own motion whether a term in a contract on which the debt is based is unfair, when the authority hearing the application for an order for payment does not have the power to make such an assessment (judgment of 18 February 2016, Finanmadrid EFC, C‑49/14, EU:C:2016:98, paragraphs 50 to 55).

( 35 ) See point 53 of this Opinion.

( 36 ) The referring court stated that the ECHR has constitutional status in Austria. See point 18 of this Opinion.

( 37 ) Judgment of 6 October 2015 (C‑69/14, EU:C:2015:662, paragraph 34).

( 38 ) Judgment of 6 October 2015, Târşia (C‑69/14, EU:C:2015:662, paragraphs 27 and 32).

( 39 ) See, in particular, judgments of 29 October 2009, Pontin (C‑63/08, EU:C:2009:666, paragraph 45); of 26 January 2010, Transportes Urbanos y Servicios Generales (C‑118/08, EU:C:2010:39, paragraph 34); of 8 July 2010, Bulicke (C‑246/09, EU:C:2010:418, paragraph 27); and of 19 July 2012, Littlewoods Retail and Others (C‑591/10, EU:C:2012:478, paragraph 31).

( 40 ) See, to that effect, judgments of 15 September 1998, Edis (C‑231/96, EU:C:1998:401, paragraphs 36 and 37); of 15 September 1998, Spac (C‑260/96, EU:C:1998:402, paragraphs 20 and 21); of 17 November 1998, Aprile (C‑228/96, EU:C:1998:544, paragraphs 20 and 21); and of 9 February 1999, Dilexport (C‑343/96, EU:C:1999:59, paragraphs 27 and 28).

( 41 ) Judgments of 29 October 2009, Pontin (C‑63/08, EU:C:2009:666, paragraphs 45 and 46), and of 19 July 2012, Littlewoods Retail and Others (C‑591/10, EU:C:2012:478, paragraph 31).

( 42 ) See points 49 to 55 of this Opinion.

( 43 ) See Opinion 2/13 (Accession of the European Union to the ECHR) of 18 December 2014 (EU:C:2014:2454, paragraph 176) and the judgment of 6 March 2018Achmea (C-284/16, EU:C:2018:158, paragraph 37).

( 44 ) See Press Release ECHR 143 (2018) of 12 April 2018, ‘La France ratifie le [protocole No 16] et déclenche son entrée en vigueur’ [France ratifies Protocol No 16 and triggers its entry into force], available at http://hudoc.echr.coe.int/eng-press?i= 003-6057606-7791962.

( 45 ) The chart of signatures and ratifications of Protocol No 16 is available at https://www.coe.int/fr/web/conventions/full-list/-/conventions/treaty/214/signatures?p_auth=SjCbMEEd.

( 46 ) See points 19 and 20 of this Opinion.

( 47 ) See point 29 of this Opinion.