Non-EU Courts on the Enforcement of Spain’s Intra-EU Arbitration Awards: Sovereign Immunity and EU Law Objections

Spain has resisted recognition and enforcement of intra-EU Energy Charter Treaty (ECT) awards by invoking the Court of Justice of the European Union (CJEU) decisions in Achmea and Komstroy. While Spain’s arguments have largely succeeded in blocking enforcement within the EU, non-EU courts have upheld the awards against Spain. This article surveys decisions from Switzerland, Australia, the United Kingdom, and, more recently, the United States on the enforceability of intra-EU awards against Spain. 

The Awards Against Spain

In 2007, the Spanish Government issued Royal Decree 661/2007, setting up a system of feed-in tariffs and subsidies to encourage investments in Spain’s renewable energy sector (the 2007 Decree). Spain later repealed the 2007 Decree in 2013 and 2014.

As an ECT signatory, Spain undertook obligations under public international law to protect the investments of investors from other signatory states (including other EU Member States), and, under Article 26 of the ECT, gave unconditional consent to submit qualifying investor-state disputes to arbitration, including ICSID and UNCITRAL proceedings.

Following Spain’s repeal of the 2007 Decree, numerous investors, including EU investors, commenced arbitration alleging Spain’s breach of the ECT’s fair and equitable treatment standard. Tribunals have issued the following awards (plus interest):

• Infrastructure Services Luxembourg v Spain (ISL): 25 May 2018, €101 million.^[1]
• NextEra v. Spain (NextEra): 31 May 2019, €290.6 million.^[2]
• AES Solar and others v Spain (assigned to Blasket Renewable LLC) (Blasket Renewable): 28 February 2020, €91.1 million.^[3]
• 9REN Holding v Spain (9Ren): 31 May 2019, €41.76 million.^[4]
• EDF v Spain: 11 April 2023, €29.6 million.^[5]

(collectively, the Awards)^[6]

Spain’s EU Law Objections

Achmea and Komstroy

In the proceedings leading to the Awards, Spain challenged the tribunals’ jurisdiction by relying on the CJEU’s rulings in Achmea (2018) and Komstroy (2021).

In Achmea, the CJEU considered that tribunals may interpret EU law or protections that overlap with the EU Treaties’ fundamental freedoms in deciding a dispute regarding substantive protections under an investment treaty. However, such tribunals cannot ensure the uniform interpretation of EU law through the preliminary reference mechanism under Article 267 of the Treaty on the Functioning of the European Union (TFEU). Further, Article 344 of the TFEU prohibits member states from submitting a dispute concerning EU law to other dispute settlement mechanisms outside of the EU legal framework. Thus, the CJEU held that Articles 267 and 344 of the TFEU “must be interpreted as precluding a provision in an international agreement concluded between [EU] member states under which an investor from one of those Member States may, in the event of a dispute concerning investments in the other Member State, bring proceedings against the [latter] before an arbitral tribunal whose jurisdiction [they] have undertaken to accept.”^[7]

The CJEU in Komstroy extended that analysis to the ECT. It held that because the EU is a signatory to the ECT, the ECT is itself an “act of Union law” that must be interpreted in a manner that is compatible with the EU treaties. As such, Article 26 of the ECT (containing the arbitration mechanism) has to be resolved in favour of EU law (i.e., interpreted as not applying to intra-EU disputes).

Spain contended in the arbitrations that because of the CJEU’s holdings in Achmea and Komstroy, which have the dual effect of “EU law” and “applicable international law”, the conflict between the EU treaties following Achmea and Komstroy and public international law must be resolved in favour of EU law due to the principle of primacy. The effect of which is that Article 26 of the ECT could not apply to intra-EU disputes, and Spain therefore lacked capacity or could not otherwise consent to arbitrate with EU investors, thus depriving the ICSID and UNCITRAL tribunals of their jurisdiction to hear the arbitrations and render the Awards (Spain’s EU Law Objections).

However, tribunals have consistently rejected Spain’s objections, holding that their jurisdiction is governed by the ECT and the applicable arbitration conventions under public international law, not EU law. As put by the tribunal in NextEra, the intra-EU nature of the parties “does not make the present dispute into a purely European one” or “strip the present dispute of its international aspects”, and the tribunals’ jurisdiction “[cannot] be resolved in favour of EU law”.^[8]

Enforcement Issues in the EU

Notwithstanding the tribunals’ findings, EU policy developments have thwarted enforcement efforts within the EU. On 15 January 2019, twenty‑two Member States (including the Netherlands, Luxembourg, and France) issued a declaration affirming that EU law prevails over intra‑EU investment treaties.^[9] A further declaration of 26 June 2024 expressed a common understanding that Article 26 of the ECT “cannot extend and could not have been extended” to intra‑EU arbitration.^[10]

Separately, the European Commission’s 2017 State Aid Decision found Spain’s support scheme under the 2007 Decree constituted unauthorised State aid under Article 107 of the TFEU and stated that any compensation awarded by arbitral tribunals on that basis would itself constitute State aid, which is outside the competence of the tribunal and subject to notification and approval under Article 108 of the TFEU.^[11]

These positions reflect the EU’s view that Spain’s pecuniary obligations under the Awards are invalid as a matter of EU law and are in any event caught by the State aid regime and cannot be paid absent the Commission’s approval.

Foreign Enforcement of Awards against Spain

EU investors have therefore pursued recognition and enforcement in non-EU jurisdictions that are parties to the ICSID or New York Conventions. In essence, courts of signatory states to these conventions must respectively enforce ICSID awards as if they were final judgments of their own courts under Articles 53-55 of the ICSID Convention and recognise and enforce UNCITRAL awards as binding under Article III of the New York Convention.

Non-EU courts are, importantly, not bound by the decisions of the CJEU or the European Commission. Spain has therefore contested recognition and enforcement abroad, frequently reframing its EU‑law objections to support claims of sovereign immunity under those local jurisdictions.

The following sections summarise how courts in Switzerland, Australia, the United Kingdom, and the United States have addressed the different permutations of Spain’s EU Law Objections.

Switzerland

In EDF v Spain, the French investor sought recognition and enforcement in Switzerland of its UNCITRAL award against Spain. Spain’s principal objection was that there was no valid arbitration agreement because, following Achmea and Komstroy, EU law barred Spain from consenting to arbitration with EU investors under Article 26 of the ECT.

In its judgment of 3 April 2024, the Swiss Federal Tribunal first held that the ECT, as an instrument of public international law, must be construed in accordance with the rules of the ECT and the Vienna Convention on the Law of Treaties (VCLT). Read in good faith and in light of its object and purpose, the ECT’s “unconditional consent” to submit “any dispute” to arbitration, together with its exhaustive exceptions, does not support an implied exclusion of intra-EU disputes. The Swiss Federal Tribunal further commented that if such an exclusion had been intended, it would have been expressed through a disconnection clause, which the ECT lacks.^[12]

The Swiss Federal Tribunal then reviewed Achmea and Komstroy. It considered that those rulings were not binding on non-EU states and refused to attach any “particular value” to the CJEU’s rulings as they were “essentially, if not exclusively” based on preserving the autonomy of EU law without engaging with international law or treaty interpretation rules.^[13]

The Swiss Federal Tribunal also rejected the premise that investment arbitration is inherently incompatible with the EU Treaties:  the preliminary reference mechanism to the CJEU under Article 267 of the TFEU does not confer “exclusive jurisdiction” on the CJEU over the interpretation of EU law (to the exclusion of ICSID Tribunals), nor does the prohibition on Member States from submitting disputes concerning the interpretation of the EU Treaties to other methods of settlement under Article 344 of the TFEU apply to investor–state disputes that are governed by public international law. The Swiss Federal Tribunal further opined that even if it is assumed that a conflict between the ECT’s arbitration agreement and EU law exists, nothing under public international law suggests that the TFEU should prevail over the terms of the ECT.^[14]

Accordingly, the Swiss Federal Tribunal rejected Spain’s objection and confirmed that Spain’s consent to arbitrate under Article 26 of the ECT extends to intra‑EU disputes. The Swiss Federal Tribunal’s approach resolves Spain’s EU Law Objections by interpreting the ECT in accordance with public international law, over which the CJEU’s rulings have no primacy in a non-EU state.

Australia

Spain initially invoked sovereign immunity in respect of Australia’s ICSID Convention obligation to “recognise” and “enforce” ICSID awards. In Infrastructure Luxembourg SARL v Kingdom of Spain [2023] HCA 1, Spain argued that its obligations under Article 54 of the ICSID Convention to “recognise as binding” and “enforce” the pecuniary obligations of an ICSID award were insufficiently clear to amount to an express waiver of sovereign immunity under the Australian Foreign States Immunities Act 1985 (Australian FSIA).

The High Court of Australia (HCA) rejected Spain’s argument. Applying the VCLT, the HCA interpreted Articles 53 to 55 of the ICSID Convention in light of their text, context, and purpose and held that Spain’s agreement to recognition and enforcement under the ICSID Convention was sufficiently clear to constitute a waiver of jurisdictional immunity under s 10(2) of the Australian FSIA for proceedings to recognise and enforce the award. By contrast, “execution” (e.g., measures against Spanish assets in Australia) is preserved to domestic law: Article 54(3) allocates execution to the forum’s judgment‑execution regime, and Article 55 confirms that nothing in Article 54 derogates from state immunity from execution. The HCA therefore concluded that, by entering the ICSID Convention, Spain waived immunity “by agreement” for recognition and enforcement proceedings.^[15]

Spain also requested the HCA to “take cognisance” of Achmea and Komstroy in assessing whether Spain submitted to Australian jurisdiction. The HCA rejected that request, holding that the relevant “waiver” arose from Spain’s accession to the ICSID Convention, which included an agreement to the consequences of an ICSID award.

This EU law point was later developed in subsequent Federal Court proceedings (FCA). On appeal in Blasket Renewable Investments LLC v Kingdom of Spain [2025] FCA 1028, Spain developed its Achmea and Komstroy case in conjoined proceedings concerning the Blasket Renewable, ISL, 9REN, and NextEra awards. Spain reframed its objections as follows: first, Australia’s obligation under Article 54 of the ICSID Convention to recognise and enforce applies only to “binding” awards; and second, because EU law is said to operate as applicable international law, a conflict arises between Spain’s EU‑treaty duties and its ICSID obligations to comply with an adverse award, which—by virtue of the primacy of EU law—must be resolved in favour of EU law.

The FCA nevertheless held that the EU principle of primacy operates only within the EU legal order as “supranational law” and does not resolve conflicts on the international plane. Achmea and Komstroy did not nullify the arbitration agreements or extinguish Spain’s international obligations; at most, they established an incompatibility within the intra-EU context and conferred an obligation on Member States to withdraw from the conflict. As a matter of public international law, Spain remains bound to comply with the ICSID awards, and Australia, as an ICSID Contracting State, is obliged under Article 54 to recognise and enforce them.^[16]

While the Australian courts’ conclusions align in outcome with the Swiss Federal Tribunal—namely, that Spain’s intra‑EU objections do not bar international recognition and enforcement outside the EU—the FCA did not go so far as the Swiss Federal Tribunal to declare “no apparent conflict” between EU law and the ECT. Rather, it treated Spain’s EU Law Objections as limited in effect to the EU system as “supranational law”.

United Kingdom

By way of context, the Arbitration (International Investment Disputes) Act 1966 (1966 Act) implements the United Kingdom’s obligations under the ICSID Convention by providing for “registration” of ICSID awards in the High Court. The State Immunity Act 1978 (SIA) confers general adjudicative immunity, subject to exceptions including submission to jurisdiction by prior written agreement (section 2(2)) and agreement to arbitrate (section 9).

In Infrastructure Luxembourg S.À.R.L. and others v Spain [2024] EWHC 1226 (Comm), Spain sought to set aside the investor’s registration of the award on three related grounds:  (1) the High Court lacked the jurisdiction to grant the registration because Spain benefited from the general immunity under the SIA; (2) Spain had not waived immunity because there was no “written agreement to arbitrate”, as Article 26 of the ECT did not extend to EU investors post‑Achmea and Komstroy; and (3) the CJEU’s judgments have effect as international law, and any conflict between Spain’s treaty obligations must be resolved in favour of EU law by reason of primacy.

The High Court rejected Spain’s application. First, applying the Supreme Court’s decision in Micula,^[17] Fraser J held that, for ICSID awards, a respondent state cannot raise defences beyond the limited remedies in Article 52 of the ICSID Convention; Spain’s objections therefore provided no defence to registration.^[18] Second, while recognising the post‑Achmea and Komstroy tension between EU law and the ICSID and ECT regimes, the High Court resolved it by reference to public international law and Article 30 of the VCLT: Spain remains bound by the ICSID obligations as regards third party states and therefore cannot rely on EU law to dilute the United Kingdom’s duty to recognise and enforce under the ICSID Convention.^[19] Third, because Spain’s ICSID and ECT obligations persist as a matter of international law, Spain’s accession to the ICSID Convention constituted a written agreement to arbitrate for SIA purposes, amounting to a waiver of adjudicative immunity under section 2 of the SIA.^[20]

Spain appealed the High Court’s findings in the conjoined appeal involving Infrastructure Luxembourg S.À.R.L. and others v Spain and Border Timbers Ltd and another v Republic of Zimbabwe [2024] EWCA Civ 1257. The Court of Appeal dismissed the appeal. It accepted that adjudicative immunity applies to registration proceedings under the 1966 Act but held that Spain submitted to the jurisdiction within section 2 by ratifying the ICSID Convention, under which Article 54 imposes an “unmistakable obligation to recognise and enforce”, an approach the Court of Appeal considered “plainly correct” after drawing support from the HCA proceedings.^[21] Having held that Spain waived sovereign immunity under section 2 of the SIA, the Court of Appeal did not need to address Spain’s further jurisdictional challenge under section 9 of the SIA on whether Spain had “agreed to arbitrate” with EU nationals under the ECT based on the Achmea and Komstroy arguments.

For completeness, the Court of Appeal declined to extend the same analysis to New York Convention awards, noting that Article III’s “in accordance with the rules and procedure” qualifier does not evince an equivalent, unmistakable waiver of immunity as under Article 54 of the ICSID Convention.

In summary, the English courts’ approach acknowledges a tension between EU law (following Achmea and Komstroy) and the ICSID and ECT regimes. But, like the Australian courts, it resolves this purported conflict through application of public international law, in which Spain’s EU Law Objections could not alter the United Kingdom’s treaty obligations under the ICSID Convention as a non-EU state.

On state immunity, the English courts align with Australia in treating Article 54 of the ICSID Convention as a waiver of adjudicative immunity for recognition and enforcement. But a distinct UK feature is that, following the Court of Appeal’s judgment, ICSID awards are in principle registrable and enforceable against States as they have “waived” state immunity by ratifying the ICSID Convention. It may therefore be the case that Achmea and Komstroy jurisdictional points may not need to be litigated at registration, as any ICSID awards would automatically be in principle registrable in the English courts.

However, that approach is pending permission to appeal and is nevertheless confined to ICSID awards. By contrast, UNCITRAL awards do not benefit from the same analysis: Article III of the New York Convention (“in accordance with the rules and procedure” of the forum) was not read as an unmistakable waiver of adjudicative immunity (see CA at [102(i)]).

United States

The EU investors in NextEra, 9REN, and Blasket Renewable sought enforcement in the United States under the Foreign Sovereign Immunities Act (US FSIA).  Two gateways are relevant: the waiver exception, where a state has waived immunity “explicitly or by implication” (28 U.S.C. § 1605(a)(1)), and the arbitration exception, which confers jurisdiction to confirm an award made pursuant to “an agreement to arbitrate” where the agreement or award is governed by a treaty in force for the United States calling for recognition and enforcement (28 U.S.C. § 1605(a)(6)), such as the ICSID or New York Conventions. 

At first instance, the district courts split. In NextEra and 9REN, the courts denied Spain’s motions to dismiss, holding that the arbitration exception is satisfied by a prima facie showing of an agreement and an award—typically by producing the ECT, the notice of arbitration, and the tribunal’s decision. Spain’s Achmea and Komstroy objections were treated as challenges to validity/arbitrability for the merits, not as jurisdictional defects under the US FSIA.^[22]  By contrast, in Blasket Renewable, the district court dismissed for lack of jurisdiction, characterising Spain’s case as a capacity objection that negated the existence of any “agreement to arbitrate” under Article 26 of the ECT.^[23]

On consolidated appeal, the D.C. Circuit reconciled the split and held that jurisdiction exists under the US FSIA’s arbitration exception. The court identified three jurisdictional facts the petitioner must establish: (i) an agreement to arbitrate, (ii) an arbitral award, and (iii) a treaty potentially governing recognition and enforcement. On the text, Article 26 of the ECT supplied the relevant agreement: Spain is a Contracting Party and the petitioning companies are “investors of another Contracting Party” (the Netherlands and Luxembourg). Echoing the Swiss approach, the D.C. Circuit noted that nothing in the ECT suggests an intra‑EU carve‑out (for example, via a disconnection clause). 

Spain did not dispute the awards or the applicable treaties; its objection targeted the “existence” of an agreement via Achmea and Komstroy. The D.C. Circuit held that such arguments go to the scope/arbitrability of a concededly existing agreement and therefore to enforceability on the merits, not to US FSIA jurisdiction. To make the issue jurisdictional, a sovereign must attack the existence or validity of the agreement itself. Spain did not: it challenged only whether the ECT’s standing offer to arbitrate extended to intra‑EU disputes, which is a question as to the “scope” of the underlying arbitration agreement, not a jurisdictional defect on the factual existence of the agreement itself that engages the US FSIA jurisdiction.^[24] 

Having found jurisdiction under the arbitration exception, the D.C. Circuit left open the separate waiver gateway (treaty ratification as implied waiver) as unnecessary to decide. Subsequently, the district court granted summary judgment in favour of the NextEra, 9REN, and Blasket petitioners. 

In sum, the U.S. courts affirmed jurisdiction to confirm the awards, but in a manner distinct from Switzerland, the United Kingdom, and Australia. First, the D.C. Circuit confined its analysis to sovereign immunity under the US FSIA and did not consider the merits of Spain’s Achmea and Komstroy arguments, treating those objections as issues of arbitrability/enforceability rather than issues relating to the US FSIA jurisdiction. Second, the court expressly left open whether treaty ratification effects an implied waiver under § 1605(a)(1) of the US FSIA. The upshot is that the United States remains a viable forum for EU investors to seek confirmation of intra‑EU awards notwithstanding Spain’s EU Law Objections. 

Conclusions

While EU institutions take the position that intra‑EU ECT awards are unenforceable post‑Achmea and Komstroy, recent decisions in Switzerland, Australia, the United Kingdom, and the United States indicate that EU investors can, in principle, pursue recognition and enforcement outside the EU. That said, each jurisdiction has reached that result through its own legal framework on state immunity and considerations of public international law. The disparate approaches between these jurisdictions point to a general openness to recognition and enforcement, but under divergent legal frameworks.

The practical value of enforcement outside of the EU, however, remains uncertain due to EU State aid constraints. The European Commission’s decision of 24 March 2025 regarding the ISL award directed Spain to ensure that no payment, execution, or implementation occurs.^[25] Consistent with this approach, the Amsterdam District Court’s judgment of 5 March 2025 treated payment under the AES/AEF award (assigned to Blasket Renewable, a US-based company) as unlawful State aid recoverable from the assignors.^[26]

Non‑EU judgments may offer meaningful avenues for recognition and enforcement strategy in terms of intra-EU ICSID awards, but the realisation of the awards will depend on forum‑specific rules on immunity and execution and on how EU State aid measures affect any eventual payment. Pending appeals in the United Kingdom and United States also add a further layer of uncertainty.

^[1]  Infrastructure Services Luxembourg S.à.r.l. and Energia Termosolar B.V. (formerly Antin Infrastructure Services Luxembourg S.à.r.l. and Antin Energia Termosolar B.V.)​ v. Kingdom of Spain, ICSID Case No. ARB/13/31.

^[2] NextEra Energy Global Holdings B.V. and NextEra Energy Spain Holdings B.V. v. Kingdom of Spain, ICSID Case No. ARB/14/11.

^[3] AES Solar and others (PV Investors) v. Kingdom of Spain, PCA Case No. 2012-14. This claim was later assigned to Blasket Renewable LLC, a US incorporated company. However, it should be caveated that not all jurisdictions recognise the assignability of an ICSID award. Recently, the English Commercial Court has ruled that as a matter of construction, ICSID awards rendered under the ECT are not assignable, and thwarted the substitution of Blasket Renewable LLC as a claimant in OperaFund Eco-invest Sicav Plc and others v the Kingdom of Spain [2025] EWHC 2874.

^[4] 9REN Holding S.A.R.L v. Kingdom of Spain, ICSID Case No. ARB/15/15

^[5] EDF Energies Nouvelles S.A. v. Kingdom of Spain, PCA Case No. AA613

^[6]  It should be noted that Spain is not the only EU member state that has been subject to arbitrations filed by EU investors. As examples, the cases of Natland v the Czech Republic PCA Case No. 2013-35 and CEF Energia BV v the Italian Republic SCC Arbitration V (2015/158) also arose out of similar retroactive changes to the applicable national renewable energy incentives regime. 

^[7] Case C-284 Slowakische Republik v Achmea BV [2018] ECLI:EU:C:2018:158.

^[8] NextEra Energy Global Holdings B.V. and NextEra Energy Spain Holdings B.V. v. Kingdom of Spain, ICSID Case No. ARB/14/11, Decision on Jurisdiction, Liability, and Quantum Principles, paras 350-351. 

^[9] Declaration of the Member States of 15 January 2019 on the legal consequences of the Achmea judgment and on investment protection, 17 January 2019.

^[10]  Declaration on the legal consequences of the judgment of the Court of Justice in Komstroy and common understanding on the non-applicability of Article 26 of the Energy Charter Treaty as a basis for intra-EU arbitration proceeding, 6 August 2024.

^[11]  European Commission Decision on State Aid SA.40348 (2015/NN), 10 November 2017.

^[12]  EDF Energies Nouvelles S.A. v. Kingdom of Spain, Judgment of the Siwss Federal Tribunal 4A 244/2023, 3 April 2024, Para 7.7.2.

^[13]  EDF v Spain, para 7.8.2. 

^[14]   EDF v Spain, 7.8.2.-7.8.3.

^[15]  Infrastructure Luxembourg SARL v Kingdom of Spain [2023] HCA 11, Paras, 43 – 58 and 75.

^[16]  Blasket Renewable Investments LLC v Kingdom of Spain [2025] FCA 1028. 186

^[17] Micula and others (Respondents/Cross Appellants) v Romania (Appellant/Cross-Respondent) [2020] UKSC 5.

^[18] Infrastructure Luxembourg S.À.R.L. and others v Spain [2024] EWHC 1226 (Comm), para 79

^[19] Infrastructure Luxembourg S.À.R.L. and others v Spain [2024] EWHC 1226 (Comm), para 85.

^[20] Infrastructure Luxembourg S.À.R.L. and others v Spain [2024] EWHC 1226 (Comm),  para 104-122.

^[21] Infrastructure Luxembourg S.À.R.L. and others v Spain [2024] EWCA Civ 1257, para 77-98.

^[22] NextEra Energy Global Holdings B.V. v. Kingdom of Spain, 656 F. Supp. 3d 201 (D.D.C. 2023), and 9REN Holding S.A.R.L. v. Kingdom of Spain, No. 19-cv-1871, 2023 WL 2016933 (D.D.C. Feb. 15 2023)

^[23] Blasket Renewable Investments, LLC v. Kingdom of Spain, 665 F. Supp 3d 1 (D.D.C. 2023.)

^[24]  NextEra Energy Global Holdings B.V. v. Kingdom of Spain, 112 F.4th 1088 (D.C. Cir. 2024).

^[25] Decision of the European Commission on the Measure State Aid SA.54155 (2021/NN) Implemented by Spain – Arbitration Award to Antin

^[26] AES Solar and others (PV Investors) v. Spain, Judgment of the Amsterdam District Court, 5 March 2025.