Opinion of Advocate General Ćapeta delivered on 3 September 2026.

Provisional text

OPINION OF ADVOCATE GENERAL

ĆAPETA delivered on 3 September 2026 ( 1 )

Case C ‑ 509/25 voestalpine Stahl GmbH, PIWAG Entsorger GmbH with the participation of:

Landeshauptmann von Oberösterreich

(Request for a preliminary ruling from the Landesverwaltungsgericht Oberösterreich (Regional Administrative Court of Upper Austria, Austria))

( Reference for a preliminary ruling – Environment – Shipment of waste – Regulation (EC) No 1013/2006 – Classification as waste listed in Annex IV – Article 28(2) – Disagreement regarding the classification of waste between the competent authorities of dispatch and destination – Legal consequence for economic operators affected by that disagreement – Effective judicial protection )

I. Introduction

1. The Landesverwaltungsgericht Oberösterreich (Regional Administrative Court of Upper Austria, Austria) is presented with proceedings brought by economic operators affected by a disagreement between the competent authorities of dispatch (here, Austria) and of destination (here, the Czech Republic) as to which waste notification procedure should be followed for movements of steel slag, a by-product of steel production.

2. The Czech authorities consider that such slag should be classified as falling under the ‘amber’ list of Annex IV to Regulation (EC) No 1013/2006 of the European Parliament and of the Council of 14 June 2006 on shipments of waste (‘the 2006 Waste Shipment Regulation’), ( 2 ) and thus be subject to the procedure of prior notification and consent. ( 3 ) That procedure, in essence, requires the competent authority of dispatch to notify the competent authority of destination of a transboundary movement of waste, and to obtain written authorisation from the latter in relation thereto. The competent Austrian authorities, however, consider that slag to fall under the ‘green’ lists of Annexes III, IIIA and IIIB to the 2006 Waste Shipment Regulation, meaning that it would be subject to the less onerous general information procedure. ( 4 )

3. Pursuant to Article 28(2) of the 2006 Waste Shipment Regulation, which is titled ‘disagreement on classification issues’, where the competent authorities of dispatch and destination cannot agree on the classification of certain types of waste, the movement of the item concerned must be made subject to the procedure of prior notification and consent. ( 5 )

4. voestalpine Stahl GmbH and PIWAG Entsorger GmbH, the applicants in the main proceedings, have brought an action before the referring court against a declaratory decision of the Austrian authorities which, when applying that provision, finds that, by virtue of the disagreement at issue, those operators must follow the procedure of prior notification and consent for any shipments of steel slag from Austria to the Czech Republic. In relation to the questions that the Court has requested guidance on in this Opinion, the applicants in the main proceedings, in essence, allege that an interpretation of Article 28(2) of the 2006 Waste Shipment Regulation which would bind the Austrian authorities in their decision-making powers with regard to the notification procedure to be followed would leave the applicants without an effective remedy, in Austria, to challenge the substantive correctness of the Czech authorities’ classification decision in respect of the slag at issue.

5. In the present proceedings, the Court is therefore, for the first time, called upon to interpret the nature of Article 28(2) of the 2006 Waste Shipment Regulation and to clarify the consequences arising from its application.

II. Facts, background and the proceedings before the referring court

6. voestalpine Stahl produces steel in Austria.

7. PIWAG Entsorger ships slag from iron and steel production from Austria to other countries, including the Czech Republic.

8. Steel slag is a by-product of the steel production process.

9. According to the order for reference, as well as the observations of the parties, prior to June 2023, the competent authorities of both Austria and the Czech Republic considered steel slag to be waste classifiable under the ‘green’ lists of Annexes III, IIIA and IIIB to the 2006 Waste Shipment Regulation. Shipments of such slag from Austria to the Czech Republic were therefore subject to the general information procedure provided for in Article 3(2) of the 2006 Waste Shipment Regulation.

10. On 28 March 2023, the Czech authorities informed the competent Austrian authorities that, as of 1 July 2023, they would consider the steel slag at issue to be waste classifiable under the ‘amber’ list of Annex IV to the 2006 Waste Shipment Regulation if it was intended as backfill or for other surface applications. ( 6 ) Those authorities explained that that change of position was necessary in order to ensure that imported steel slag ‘be in accordance with Czech national legislation relating to environmental and health protection and public safety’. ( 7 ) Accordingly, the slag could only be shipped to the Czech Republic following prior written notification and consent, in line with the procedure laid down in Article 3(1) of the 2006 Waste Shipment Regulation (‘the notification and consent procedure’).

11. On 21 April 2023, the Austrian authorities relayed the position of the Czech authorities to the Wirtschaftskammer Österreich (Austrian Chamber of Commerce). It appears uncontested that voestalpine Stahl and PIWAG Entsorger are members of that chamber.

12. On 8 June 2023, the Czech authorities issued a ‘methodological notice’ on the shipment of slag from iron and steel production. ( 8 ) That notice explains the reasons for changing the classification of the slag at issue by referring, inter alia, to the risks for the environment and human health associated with the use of slag from iron and steel production intended for use as backfill or for other surface applications. Accordingly, shipments of that type of waste should now be subject to the notification and consent procedure.

13. On 5 July 2023, voestalpine Stahl applied to the Austrian authorities for a declaratory decision that the type of steel slag produced at its site and transported to the Czech Republic, in so far as it is classified as waste, is not subject to the notification and consent procedure provided for in Article 3(1) of the 2006 Waste Shipment Regulation.

14. On 30 June 2023, PIWAG Entsorger applied for the same type of determination.

15. On 9 July 2023, the Austrian authorities issued decisions in response to those requests. In essence, those authorities explained that there was a divergence in opinion between the competent Austrian and Czech authorities as to the classification of the slag at issue under either Annex III or Annex IV to the 2006 Waste Shipment Regulation. By virtue of Article 28(2) of the 2006 Waste Shipment Regulation, the slag at issue would thus be classifiable in Annex IV thereto and be made subject to the requirement of prior written notification and consent.

16. voestalpine Stahl and PIWAG Entsorger lodged appeals against those decisions with the referring court. In essence, those operators argue that the conditions for the application of Article 28(2) of the 2006 Waste Shipment Regulation are not met. In their view, there was no disagreement capable of triggering that provision, as there exists no challengeable act by the Czech authorities and no explicit objection has been made by the Austrian authorities.

17. In its order for reference, the referring court, inter alia, voices doubt as to how it can ensure effective judicial review of the competent Czech authorities’ decision, given that the methodological notice issued by those authorities produces no binding legal effect in Austria. It also seeks to ascertain, in essence, whether the competent Austrian authorities are in a position to question the competent Czech authorities’ classification decision.

18. In those circumstances, the Landesverwaltungsgericht Oberösterreich (Regional Administrative Court of Upper Austria) decided to stay the proceedings and to refer the following questions to the Court of Justice for a preliminary ruling:

‘(1) Must Article 28(2) of [the 2006 Waste Shipment Regulation] be interpreted as meaning that there is “notified waste” within the meaning of that provision where waste was notified to the competent authority in the country of dispatch in advance in writing in accordance with Chapter 1 of Title II of the [2006] Waste Shipment Regulation?

(2) Must Article 28(2) of the [2006] Waste Shipment Regulation be interpreted as meaning that the legal consequence provided for therein – according to which the waste is to be regarded as waste listed in Annex IV to the [2006] Waste Shipment Regulation (legal consequence) – can apply to individual (notified) waste or also to entire flows of waste?

(3) Must Article 28(2) of the [2006] Waste Shipment Regulation, in conjunction with requirements under primary law, in particular the free movement of goods under Article 34 et seq. TFEU and Article 47 of the Charter of Fundamental Rights [of the European Union] (“the Charter”), be interpreted as meaning that the legal consequence, for the person affected by it, arises at the time at which the authorities fail to reach agreement or at another time, in particular after the expiry of a reasonable period after the time at which the authorities fail to reach agreement?

(4) Must Article 28(2) of the [2006] Waste Shipment Regulation, in conjunction with requirements under primary law, in particular the free movement of goods under Article 34 et seq. TFEU and Article 47 of the Charter, be interpreted as meaning that the application of the legal consequence presupposes the adoption of a national implementing measure with regard to notified waste?

If Question 4 is answered in the affirmative:

(5) Does Article 28(2) of the [2006] Waste Shipment Regulation, in conjunction with Article 47 of the Charter, require the adoption of a national legal act by the competent authority of dispatch or the competent authority of destination or the competent authorities of dispatch and [of] destination, in respect of which (in each case) the person affected by the legal consequence has an effective legal remedy enabling that person to challenge that act?

(6) In a procedure to determine whether a particular shipped substance is subject to the procedure of prior written notification and consent in accordance with Chapter 1 of Title II of the [2006] Waste Shipment Regulation, does Article 28(2) of the [2006] Waste Shipment Regulation preclude an authority of dispatch from examining the compatibility with EU law of a national act by the competent authority of destination which relates to the application of the legal consequence under Article 28(2) of the [2006] Waste Shipment Regulation?’

19. Written observations were submitted to the Court by the applicants, the Czech, Austrian and Polish Governments and the European Commission. No hearing was held.

III. Analysis

20. In the present case, there is a disagreement between the competent authorities in Austria, the country of dispatch, and the competent authorities in the Czech Republic, the country of destination, about how to classify waste consisting of slag from steel production. Such an administrative disagreement triggers the application of Article 28(2) of the 2006 Waste Shipment Regulation, the legal consequence of which is that the economic operators which ship that waste are subject to the notification and consent procedure laid down in Article 3(1) thereof, rather than the less burdensome general information procedure, as laid down in Article 3(2) of the same regulation.

21. The fifth and sixth questions of the referring court, in relation to which the Court has asked for my assistance, enquire as to how to ensure judicial review of the legal consequences arising from the application of Article 28(2) of the 2006 Waste Shipment Regulation. By the fifth question, the referring court, in essence, wishes to know whether the principle of effective judicial protection requires that the authorities of the Member State of dispatch or of the Member State of destination, or both, issue an act that is challengeable by the economic operator affected by the application of Article 28(2) before a court of law. By the sixth question, the referring court, in essence, wishes to know whether the competent authority of dispatch may question a classification of waste by the competent authority of destination with which it does not agree.

22. I am of the view that the answer to the fifth question depends on the answer to the sixth question, which is why I propose to reverse the order in which I will analyse those two issues (Sections B and C). However, before I engage with those questions, I will briefly discuss the context and purpose of Article 28(2) of the 2006 Waste Shipment Regulation (Section A).

A. Article 28 of the 2006 Waste Shipment Regulation

23. The 2006 Waste Shipment Regulation establishes procedures and control regimes for the cross-border shipment of waste from one Member State to another, as well as from the European Union to a third country and vice versa. Its main objective is the protection of the environment and human health. ( 9 )

24. In principle, the 2006 Waste Shipment Regulation requires that the cross-border shipment of waste is managed through cooperation between the competent authorities of dispatch and destination. ( 10 )

25. However, at times, there might be disagreement among the relevant competent authorities, be it about the treatment of a particular material as waste, the type of classification to adopt as regards the waste at issue or the necessary treatment to be carried out in respect of that waste. In those situations, Article 28 of the 2006 Waste Shipment Regulation finds application.

26. That provision is entitled ‘Disagreement on classification issues’ and forms part of Chapter 5 of Title II on general administrative provisions. The first three paragraphs thereof relate solely to the question of how to resolve conflicting opinions between the competent authorities of dispatch and destination in the classification or treatment of waste and non-waste. They therefore provide for conflict rules that resolve administrative disagreements, thereby determining the applicable waste shipment procedure . ( 11 )

27. The first paragraph of that provision concerns a situation in which the competent authorities cannot agree on whether a particular material constitutes waste in the first place; that is, a situation in which one competent authority considers the material at issue waste and the other competent authority seeks to treat said material as non-waste. Article 28(1) of the 2006 Waste Shipment Regulation resolves that disagreement by providing that the material at issue is to be treated as waste. The situation in the present case does not concern that type of dispute.

28. The second paragraph of the same provision applies when there is agreement that a material constitutes waste, but there is disagreement as to how to classify said waste. It is that paragraph which applies in the present case, given that there is disagreement between the competent authorities of dispatch and destination over whether the steel slag at issue constitutes waste classifiable under the ‘green’ lists of Annexes III, IIIA and IIIB to the 2006 Waste Shipment Regulation or the ‘amber’ list of Annex IV thereto. Article 28(2) of that regulation resolves that disagreement by means of a conflict rule in favour of the ‘amber’ list of Annex IV: ‘the waste shall be regarded as listed in Annex IV’.

29. Lastly, and for completeness, the third paragraph of Article 28 of the 2006 Waste Shipment Regulation covers a situation in which there is disagreement between the competent authorities of dispatch and destination as regards the type of waste treatment operation to be performed: recovery or disposal. Here, too, the EU legislature laid down a conflict rule to be applied: in that circumstance ‘the provisions regarding disposal shall apply’.

30. What those paragraphs collectively evidence is that, in all three scenarios foreseen by the EU legislature, the conflict rules laid down in Article 28(1) to (3) of the 2006 Waste Shipment Regulation resolve the disagreement between the competent authorities of dispatch and destination in favour of the respectively stricter option for dealing with the material at issue. That legislative choice is in line with the general aim of the 2006 Waste Shipment Regulation, as it adopts a solution which is more beneficial to the protection of the environment and human health. ( 12 )

31. Article 28 of the 2006 Waste Shipment Regulation thus mandates a particular type of administrative procedure to be followed in case of disagreement in order to enable the shipment of a specific type of waste from one Member State to another. ( 13 )

32. That provision, however, does not resolve the substantive question of how to classify the waste at issue, ( 14 ) nor does it preclude the competent authorities of destination from dealing with the shipped material, following its arrival, in accordance with compatible national legislation. ( 15 )

33. In essence, that is also the reading put forward by the referring court, voestalpine Stahl, PIWAG Entsorger, the Austrian Government and the Commission.

34. With those elements in mind, I will now turn first to the sixth and then to the fifth question put to the Court.

B. The sixth question

35. By its sixth question, the referring court wishes to know whether Article 28(2) of the 2006 Waste Shipment Regulation leaves open the possibility, on the side of the competent authority of dispatch, to disregard the legal consequence arising from a disagreement with the competent authority of destination as regards the classification of the waste at issue. In the present case, that consequence consists in classifying the steel slag at issue as falling under the ‘amber’ list of Annex IV to the 2006 Waste Shipment Regulation, with the effect that it is subject to the notification and consent procedure provided for in Article 3(1) of that regulation.

36. In other words, by the sixth question, the referring court asks whether, in the circumstances of the present case, the competent Austrian authorities may decide not to trigger the notification and consent procedure and instead permit the applicants in the main proceedings to continue treating the slag at issue as falling under the ‘green’ lists of Annexes III, IIIA and IIIB and to follow the less onerous general information procedure.

37. I consider the answer to that question to be clear: the policy choice made by the EU legislature does not leave any margin of discretion to the competent authorities that are in disagreement as to whether to depart from the administrative procedure laid down in that provision. Those parties cannot therefore unilaterally depart from it. ( 16 )

38. In other words, during the period of disagreement , the competent authorities of the Member State of dispatch or destination have no choice but to follow the procedure or carry out the treatment laid down in Article 28 of the 2006 Waste Shipment Regulation. ( 17 )

39. In the context of the present case, that means that the competent Austrian authorities must, at least temporarily, require the applicants in the main proceedings to follow the notification and consent procedure required by Article 28(2) of the 2006 Waste Shipment Regulation.

40. In view of the overarching objective of the 2006 Waste Shipment Regulation and the possible environmental and/or human health consequences that may arise from the waste being stored or treated incorrectly by virtue (and during the period) of a disagreement between the competent authorities of dispatch and destination, I certainly understand why the EU legislature opted for the use of mandatory administrative conflict rules which favour a more cautious treatment of the waste at issue.

41. In fact, a different interpretation, that is to say, one in which either of those authorities would have discretion as to whether to act in accordance with the consequences resulting from Article 28(1) to (3) of the 2006 Waste Shipment Regulation or to handle the waste at issue in its own way, which may be less strict, would introduce a risk of undermining the precautionary approach that that provision pursues. ( 18 ) It would also render those conflict rules pointless.

42. Accordingly, I propose that the Court interpret Article 28(2) of the 2006 Waste Shipment Regulation as precluding the competent authority of dispatch from reviewing the compatibility with EU law of an act of the competent authority of destination which relates to the application of that provision or from unilaterally deciding not to apply the procedure provided for therein.

C. Fifth question

43. By its fifth question, the referring court, in essence, wishes to know which remedies must be available to an economic operator that considers that the classification resulting from the application of Article 28(2) of the 2006 Waste Shipment Regulation by the competent authority of dispatch is incorrect when applied to the material it intends to ship to another Member State.

44. As I have explained, Article 28 of the 2006 Waste Shipment Regulation is limited to resolving the administrative conflict linked to a disagreement concerning the classification of waste. That provision also lays down a particular legislative choice as to the shipping procedure to be applied to said waste. While, therefore, Article 28 enables the shipment of waste subject to a disagreement, it does not resolve the substantive dispute relating to the correct classification or treatment of that material.

45. As the facts of the main proceedings show, while that legislative choice enables waste shipments to continue during the period of disagreement between the competent authorities of dispatch and destination, it creates certain downstream difficulties.

46. For the competent authority of dispatch or destination which is in disagreement with the competent authority of another Member State in relation to classification, the consequence is, as explained in the proposed answer to the sixth question, that it must administer a stricter classification and/or treatment procedure than what it may consider appropriate.

47. For the economic operators at issue, the relevant disagreement might result, at least temporarily, in a more cost- and time-intensive procedure or treatment, which, if not followed, could lead to additional financial and non-financial consequences. ( 19 )

48. In that regard, prior to the adoption of the 2006 Waste Shipment Regulation, the Court recognised that ‘the risk of … different classifications is inherent in the system established by [the 1993 Waste Shipment Regulation], which confers simultaneously on all the competent authorities the responsibility of ensuring that the shipments are carried out in accordance with the Regulation.’ ( 20 )

49. Nevertheless, in the 2006 Waste Shipment Regulation, the EU legislature did not provide for a mechanism to resolve the substantive conflict underlying the procedural treatment prescribed by Article 28 thereof.

50. That regulation does not require ‘mutual recognition’ of the respective substantive position of the other competent authority, nor does it centralise the resolution of the underlying substantive dispute, for instance, by vesting the Commission or another EU body with the power to resolve disagreements between national administrative authorities by means of a binding decision. Centralising the resolution of administrative disputes at EU level was the choice of the EU legislature in certain other frameworks, ( 21 ) in which a binding decision adopted at EU level could then be the subject of annulment proceedings before the General Court, thereby removing all uncertainty regarding the appropriate route to be followed. ( 22 )

51. In view of the absence of any other method of conflict resolution, the only way to resolve that impasse is through the competent courts of the Member States. ( 23 )

52. To my mind, that conclusion readily arises from Article 28(4) of the 2006 Waste Shipment Regulation, which clarifies that the procedural conflict rules provided for in paragraphs 1 to 3 of that provision leave untouched the possibility of accessing the competent courts to resolve substantive disputes relating to the classification or treatment of waste. ( 24 )

53. That provision might be understood as an expression of the principle of effective judicial protection, as enshrined in Article 47 of the Charter. The latter principle requires that an economic operator concerned by a disagreement between the competent authorities of dispatch and destination must be given the opportunity to challenge before a court of law the legal consequence resulting from the application of Article 28(1) to (3) of the 2006 Waste Shipment Regulation. ( 25 )

54. That, in turn, requires there to exist an act capable of judicial challenge by the economic operators concerned. That act need not formally be an administrative act under national law; it might be any type of measure that is amenable to judicial review.

55. Lacking any precision in that respect in the 2006 Waste Shipment Regulation, the modalities by which the Member States ensure access to effective judicial review before their competent courts to review the consequences of the application of Article 28(2) are left to the choice of each national legal system.

56. However, the referring court not only asks whether, in order to enable effective judicial protection, the competent authorities of the Member States must adopt an act that is capable of challenge by an affected economic operator; it also wishes to know where access to a court must be provided for: in the Member State of dispatch, in the Member State of destination, or in both Member States.

57. To my mind, seeing as the application of Article 28(2) of the 2006 Waste Shipment Regulation impacts the economic operator in the Member State of dispatch, that operator must have the possibility of challenging the legal consequence of that application before a court of that Member State. That is so, notwithstanding whether there exists a possibility of initiating such proceedings also in the Member State of destination.

58. However, the issue that may occur, and which was most likely on the mind of the referring court, is that the administrative disagreement between the authority of dispatch and the authority of destination, which results in the application of Article 28(2) of the 2006 Waste Shipment Regulation, might not be known to the economic operator before it ships the waste.

59. That issue is particularly evident in a situation such as the one at issue in the main proceedings, in which, up to a certain point in time, the competent authorities of both Austria and the Czech Republic were in agreement as regards the fact that the slag at issue should be classified as ‘green’-listed waste. In such a situation, it is not inconceivable that an economic operator would continue to use the general information procedure (which, I understand, usually does not require notification before a shipment is made) in a situation in which, given the presence of a non-communicated disagreement, it should have opted for the prior information and consent procedure (which, in accordance with Article 4(1) of the 2006 Waste Shipment Regulation, requires such advance notification).

60. The consequence: an unintentional ‘illegal shipment’, within the meaning of Article 2(35) of the 2006 Waste Shipment Regulation, which triggers the take-back obligation of Article 24(1) thereof, and exposure to related costs and other administrative and/or legal consequences.

61. One may argue that an affected economic operator could always challenge a finding of illegality of the shipment at issue before the competent courts of the Member State of destination. However, that is not an optimal solution, either from the operator’s point of view (who should not be required to break the law to understand the correct procedure to be followed), or from the point of view of the protection of the environment.

62. Particularly when – as in the present case – we are concerned with waste that potentially presents risks to the environment and human health, I also fail to see how that solution would be in line with the objective of the 2006 Waste Shipment Regulation. ( 26 )

63. It would, therefore, be more in line with the objective of that regulation to require an economic operator to be informed of a disagreement between the competent authorities of dispatch and destination by the authorities of dispatch. That information should be challengeable by the economic operator, which would allow it to avoid the legal consequence of the application of Article 28(2) before a shipment is made.

64. In the situation in the main proceedings, the competent Austrian authorities appear to have satisfied that requirement of informing potentially affected economic operators when they relayed the disagreement with the competent Czech authorities to the Austrian Chamber of Commerce. In that way, notice of said disagreement appears also to have been received by the applicants in the main proceedings. ( 27 )

65. It is also clear from the case file, and was also highlighted by the Austrian Government and the Commission, that Austrian law provides for an opportunity for economic operators to challenge the substantive consequences resulting from the application of Article 28(2) of the 2006 Waste Shipment Regulation in such a situation. Austrian law enables those operators to request a declaratory decision from the competent Austrian authorities as to the classification of the waste at issue and thereby the appropriate procedure to be followed. As the facts in the main proceedings show, and as the referring court, the Austrian Government and the Commission explain, such a declaratory decision is challengeable before the competent Austrian courts.

66. That would lead me to conclude that, in the circumstances of the main proceedings, there was at least one judicial remedy in Austria making it possible, in accordance with the requirements flowing from the principle of effective judicial protection, for an economic operator affected by the application of Article 28(2) of the 2006 Waste Shipment Regulation to seek review of the substantive classification of waste shipments affected by that disagreement.

67. That being said, not all national systems may be designed in that way.

68. Choosing the modalities for providing access to the competent courts in a situation where there is a disagreement between the competent authorities of dispatch and destination will depend on the way in which a particular Member State applies the 2006 Waste Shipment Regulation. For instance, according to Article 18(3) thereof, Member States may require that they be informed about shipments which are subject to the general information procedure. The transmission of such information could be requested prior to such a shipment being made. In that way, the competent authorities could inform the operator at issue that there exists a situation of disagreement which would require a different notification and consent procedure to be followed. Such a decision could then be challenged before the competent courts of the Member State of dispatch.

69. However, I must observe that, even in a scenario such as the one in the present case, in which the Austrian system of judicial protection appears to afford the affected economic operators an avenue to challenge the substantive position taken by the competent Czech authorities, there are two significant shortcomings.

70. The first shortcoming consists of a lack of a real adversarial procedure before the competent Austrian courts, as that procedure does not involve the Czech authorities. In the scenario of the present case, an action is brought before the referring court by an economic operator challenging the substantive classification of the waste as ‘amber’-listed waste. However, the defendant, here the competent Austrian authorities, does not have an incentive to defend that classification. That authority considers that the waste should be classified as ‘green’-listed waste. At the same time, the competent Czech authorities, which consider the ‘amber’ classification to be correct, are not party to those proceedings, and the possibility that they might intervene before the competent Austrian courts depends on the Austrian national procedural rules and the Czech authorities’ initiative. Moreover, in the event that the competent first-instance court finds in favour of the economic operators concerned, there is no incentive for the competent Austrian authorities to appeal, and thus to bring the case to a court of last instance, which would be under an obligation to refer the matter to the Court of Justice.

71. The second shortcoming results from the fact that any finding of the competent Austrian courts that the classification adopted by the competent Czech authorities is incorrect is not binding on the latter authorities. That shortcoming could, however, be overcome through a reference to the Court of Justice, whose interpretation of the relevant provisions of EU law relating to the correct classification of the material at issue has erga omnes effect and therefore binds both the competent Austrian authorities (as the authorities of dispatch) and the competent Czech authorities (as the authorities of destination). ( 28 ) Nevertheless, until the national judicial proceedings reach the court of last instance in a specific case, there is no obligation to refer the matter to the Court of Justice in order to ask for an interpretation of EU law to resolve the substantive dispute at national level.

72. Despite those shortcomings, and to answer another concern of the referring court, there would be no impediment to that court requesting an interpretation of EU law from the Court of Justice, even if that would enable the referring court to find a classification decision taken by the competent authorities of another Member State to be incompatible with EU law. ( 29 )

73. Indeed, the erga omnes effect of a preliminary ruling is such as to indirectly affect also a substantive disagreement on the classification and/or treatment of waste by the competent authorities of another Member State, even in a situation in which the competent court of one Member State is not capable of setting aside an incompatible provision of the law of another Member State.

74. In the context of the main proceedings, that means that the competent Austrian courts could seek guidance on whether it is compatible with EU law that the slag at issue is, by virtue of the application of the Czech national environmental and health standards, classified as waste requiring the use of the prior notification and consent procedure provided for in Article 3(1) of the 2006 Waste Shipment Regulation. In a preliminary ruling procedure before the Court of Justice, the competent Czech authorities could then express their position through the participation of their government in those proceedings, even if they did not intervene at national level in Austria.

75. On the basis of the foregoing, I am of the view that Article 28(2) of the 2006 Waste Shipment Regulation, read in the light of Article 47 of the Charter, must be interpreted as requiring the adoption of a measure by the competent authority of dispatch, by which a person affected by the legal consequence of a disagreement between the competent authorities of dispatch and destination is informed of that disagreement and against which that person may bring proceedings before a national court, in order to challenge the substantive correctness of the classification of the waste that results from the application of Article 28(2) of that regulation.

IV. Conclusion

76. I propose that the Court answer the fifth and sixth questions referred to it by the Landesverwaltungsgericht Oberösterreich (Regional Administrative Court of Upper Austria, Austria) as follows:

(1) In answer to the fifth question: Article 28(2) of Regulation (EC) No 1013/2006 of the European Parliament and of the Council of 14 June 2006 on shipments of waste, read in the light of Article 47 of the Charter of Fundamental Rights of the European Union, must be interpreted as requiring the adoption of a measure by the competent authority of dispatch, by which a person affected by the legal consequence of a disagreement between the competent authorities of dispatch and destination is informed of that disagreement and against which that person may bring proceedings before a national court, in order to challenge the substantive correctness of the classification of the waste that results from the application of Article 28(2) of that regulation.

(2) In answer to the sixth question: Article 28(2) of Regulation No 1013/2006 must be interpreted as precluding the competent authority of dispatch from reviewing the compatibility with EU law of an act of the competent authority of destination which relates to the application of that provision or from unilaterally deciding not to apply the procedure provided for therein.

1 Original language: English.

2 OJ 2006 L 190, p. 1. While it is uncontested that the facts at issue in the main proceedings arose during the temporal scope of application of the 2006 Waste Shipment Regulation, that regulation has, in the meantime, been replaced by Regulation (EU) 2024/1157 of the European Parliament and of the Council of 11 April 2024 on shipments of waste, amending Regulations (EU) No 1257/2013 and (EU) 2020/1056 and repealing Regulation (EC) No 1013/2006 (OJ L, 2024/1157; ‘the 2024 Waste Shipment Regulation’).

3 See Article 3(1) of the 2006 Waste Shipment Regulation (which lays down that ‘shipments of the following wastes shall be subject to the procedure of prior written notification and consent … (b) if destined for recovery operations: … (i) wastes listed in Annex IV …’), read alongside Articles 4 and 9 of the 2006 Waste Shipment Regulation.

4 See Article 3(2) of the 2006 Waste Shipment Regulation (which lays down, inter alia, that ‘shipments of the following wastes destined for recovery shall be subject to the general information requirements laid down in Article 18 … (a) waste listed in Annex III or IIIB’), read alongside Article 18 thereof.

5 In full, Article 28(2) of the 2006 Waste Shipment Regulation reads as follows: ‘If the competent authorities of dispatch and of destination cannot agree on the classification of the notified waste as being listed in Annex III, IIIA, IIIB or IV, the waste shall be regarded as listed in Annex IV.’

6 According to the observations of the Czech Government, that notification was preceded by contact at various political levels between the Czech Republic and the Republic of Austria.

7 See the letter from the Austrian authorities to the Association of Economic Operators in Austria dated 21 April 2023, available at https://www.wko.at/ooe/umwelt-energie/2023-0292489-2-a--mitteilung-an-die-wko-die-voeb-und-betrof.pdf. As part of its observations in the present proceedings, the Czech Government explains that the source of that change in position lies in large quantities of steel slag containing heavy metals being shipped from Austria to the Czech Republic, which gives rise to risks of groundwater pollution. The Czech Government also explains that the incentive to ship said slag from, inter alia, Austria to the Czech Republic is linked, among other things, to stricter regulations governing the use of steel slag in Austria and substantial fees relating to its disposal.

8 That notice can be found at https://mzp.gov.cz/system/files/2024-10/OODP-Metodicke_sdeleni_struska-20230608.pdf.

9 See, in that respect, recital 1 of the 2006 Waste Shipment Regulation, which provides that ‘the main and predominant objective and component of this Regulation is the protection of the environment, its effects on international trade being only incidental’, and recital 7 thereof, which lays down that ‘it is important to organise and regulate the supervision and control of shipments of waste in a way which takes account of the need to preserve, protect and improve the quality of the environment and human health and which promotes a more uniform application of the Regulation throughout the Community’. See also judgment of 21 January 2025, Conti 11. Container Schiffahrt II (C‑188/23, EU:C:2025:26, paragraphs 62 and 63), and, to that effect, also judgment of 23 October 2025, Naturvårdsverket (Waste treatment after take-back) (C‑221/24 and C‑222/24, EU:C:2025:818, paragraph 53).

10 For example, the regulation provides for the specific obligation to designate correspondents (see Article 54 of the 2006 Waste Shipment Regulation) and to cooperate with one another in order to facilitate the prevention and detection of illegal shipments (see Article 50(5) of the same regulation). It also requires cooperation and the exchange of information between those authorities (see Article 4 et seq. thereof) to ensure the sound management of waste in the context of notification and return procedures (see Article 24 thereof). As recital 36 of the 2006 Waste Shipment Regulation furthermore states, the obligation of cooperation applies not only between the Member States but also as regards the European Union and its Member States and third countries.

11 See also, to that effect, Backes, C.W., ‘Art. 28’, in Oexle, A., Epiney, A. and Breuer, R. (eds), EG-Abfallverbringungsverordnung , Carl Heymanns Verlag, Cologne, 2010, p. 656, point 10, and Oexle, A., ‘EU-Abfallverbringungsverordnung’, in Schmehl, A. and Klement, J.H., Gemeinschaftskommentar zum Kreislaufwirtschaftsgesetz , 2nd edition, Carl Heymanns Verlag, Cologne, 2019, p. 1536, point 166, both explaining that Article 28 of the 2006 Waste Shipment Regulation must be read as an administrative ‘ Kollisionsregel ’ (conflict rules).

12 See, to that effect, recital 1 of the 2006 Waste Shipment Regulation, and judgment of 21 January 2025, Conti 11. Container Schiffahrt II (C‑188/23, EU:C:2025:26, paragraphs 45, 46 and 52).

13 See, to that effect, Opinion of Advocate General Rantos in Poland v Germany (Shipment of waste) (C‑730/23, EU:C:2026:424, point 66). See also, Proposal for a regulation of the European Parliament and of the Council on shipments of waste, COM(2003) 379 final, p. 17, point 11.

14 See, to that effect and by analogy, judgment of 14 March 2019, Commission v Czech Republic (C‑399/17, EU:C:2019:200, paragraph 53).

15 See the second sentence of Article 28(1) of the 2006 Waste Shipment Regulation.

16 That lack of discretion, which is designed to ensure the protection of the environment when movements of waste take place, is arguably a characterising element of the waste shipment framework. See, by analogy, as regards the question of whether there is discretion not to trigger the written notification and consent procedure for waste generated following damage sustained by a ship on the high seas, judgment of 21 January 2025, Conti 11. Container Schiffahrt II (C‑188/23, EU:C:2025:26, paragraph 68) (explaining that the objective of the Waste Shipment Regulation to ensure the sound management of waste and reduce shipments of it to a minimum ‘would be compromised if the person responsible for the ship concerned … had … a margin of discretion as to whether to trigger the prior written notification and consent procedure’).

17 Needless to say, this is without prejudice, in the context of the facts in the main proceedings, to the possibility of resolving the disagreement at issue bilaterally at the administrative level, or to the possibility for the competent Austrian authorities to initiate judicial proceedings before the competent courts of the Czech Republic. The competent Austrian authorities could also challenge the Czech position through its Member State by means of infringement proceedings on the basis of Article 259 TFEU or inform the Commission of a supposedly incorrect application of EU law, which, in turn, could prompt that institution to initiate proceedings on the basis of Article 258 TFEU. See, in that respect, the pending case in C‑730/23, Poland v Germany , initiated under Article 259 TFEU, or judgment of 14 March 2019, Commission v Czech Republic (C‑399/17, EU:C:2019:200), decided in an Article 258 TFEU procedure.

18 On the risk associated with introducing an element of discretion into the sound management of waste, see judgment of 21 January 2025, Conti 11. Container Schiffahrt II (C‑188/23, EU:C:2025:26, paragraph 68).

19 For example, if shipments were continued without the consent of the Czech authorities, the latter could label those shipments at issue as ‘illegal’, within the meaning of Article 2(35) of the 2006 Waste Shipment Regulation, and thus trigger the take-back obligation provided for in Article 24(1) thereof. As Article 25 of that regulation explains, those costs must be borne primarily by the notifier de facto or de jure of the ‘illegal’ shipment at issue.

20 See judgment of 27 February 2002, ASA (C‑6/00, EU:C:2002:121, paragraph 44), which concerned a classification dispute to which Council Regulation (EEC) No 259/93 of 1 February 1993 on the supervision and control of shipments of waste within, into and out of the European Community (OJ 1993 L 30, p. 1; ‘the 1993 Waste Shipment Regulation’), a predecessor of the 2006 Waste Shipment Regulation, was applicable.

21 See, for example, Article 27 of Directive (EU) 2015/2366 of the European Parliament and of the Council of 25 November 2015 on payment services in the internal market, amending Directives 2002/65/EC, 2009/110/EC and 2013/36/EU and Regulation (EU) No 1093/2010, and repealing Directive 2007/64/EC (OJ 2015 L 337, p. 35), pursuant to which the European Banking Authority resolves disagreements between the competent authorities of different Member States as to cross-border cooperation. See also Article 65 of Regulation (EU) 2016/679 of the European Parliament and of the Council of 27 April 2016 on the protection of natural persons with regard to the processing of personal data and on the free movement of such data, and repealing Directive 95/46/EC (General Data Protection Regulation) (OJ 2016 L 119, p. 1), pursuant to which the European Data Protection Board resolves disputes relating to the correct and consistent application of that regulation.

22 See, for instance, judgment of 10 February 2026, WhatsApp Ireland v European Data Protection Board (C‑97/23 P, EU:C:2026:81, paragraph 76).

23 See, in that respect, Backes, C.W., ‘Art. 28’, in Oexle, A., Epiney, A. and Breuer, R. (eds), EG-Abfallverbringungsverordnung , Carl Heymanns Verlag, Cologne, 2010, p. 656, point 10 (explaining that the conflict rules provided for in Article 28(1) to (3) of the 2006 Waste Shipment Regulation produce no substantive legal effect, so that recourse to judicial review of the substantive question resulting from those conflict rules remains open). See, along the same lines, Oexle, A., ‘EU-Abfallverbringungsverordnung’, in Schmehl, A. and Klement, J.H., Gemeinschaftskommentar zum Kreislaufwirtschaftsgesetz , 2nd edition, Carl Heymanns Verlag, Cologne, 2019, p. 1536, point 168.

24 The exact wording of that provision is that the conflict rules provided for in Article 28(1) to (3) of the 2006 Waste Shipment Regulation ‘shall be without prejudice to rights of interested parties to resolve any dispute related to these questions before a court of law or tribunal’.

25 See, to that effect, judgment of 6 October 2020, État luxembourgeois (Right to bring an action against a request for information in tax matters) (C‑245/19 and C‑246/19, EU:C:2020:795, paragraph 66 and the case-law cited).

26 See recital 7 of the 2006 Waste Shipment Regulation, which highlights the importance of organising and regulating the supervision and control of shipments of waste in a way which takes account of the need to preserve, protect and improve the quality of the environment and human health. Likewise, recall that recital 8 of that regulation highlights the requirement laid down in Article 4(2)(d) of the Basel Convention, which notes the importance of reducing shipments of hazardous waste to a minimum, consistent with the environmentally sound and efficient management of such waste.

27 See point 11 of this Opinion.

28 The classification of a material as waste and the type of waste it represents depends on the interpretation of the relevant annexes to the 2006 Waste Shipment Regulation as well as those international conventions it seeks to reflect in EU law. Likewise, it might depend on the interpretation of delegated acts, such as those that may be adopted by the Commission pursuant to Article 29(6) of the 2024 Waste Shipment Regulation to lay down criteria, such as contamination thresholds, to facilitate the harmonised classification of waste. For examples involving classification of waste under the waste shipment framework, see judgments of 1 March 2007, KVZ retec (C‑176/05, EU:C:2007:123, paragraphs 67 to 71) (concerning the classification of ‘meat-and-bone meal’); of 21 June 2007, Omni Metal Service (C‑259/05, EU:C:2007:363, paragraphs 15 to 42) (on the classification of scrap wire cables and composite waste); and of 28 May 2020, Interseroh (C‑654/18, EU:C:2020:398, paragraphs 38 to 76) (regarding the classification of a mixture of paper, paperboard and paper product waste that contained impurities).

29 See, for example, judgments of 23 November 1989, Eau de Cologne & Parfümerie-Fabrik 4711 (C‑150/88, EU:C:1989:594, paragraph 12), and of 16 April 2026, European Lotto and Betting and Deutsche Lotto- und Sportwetten (C‑440/23, EU:C:2026:299, paragraph 75 and the case-law cited).