Spain has lost its final attempt to stop investors enforcing renewable energy arbitration awards in the United States. The Supreme Court declined to take up the country’s appeal, leaving earlier rulings against it in force.
The decision cleared the way for creditors to pursue recognition and enforcement of the awards in American courts. It closed one of the biggest legal fronts Spain had opened to resist payment.
The case pitted Spain against Blasket Renewable Investments, a fund that holds a large share of the claims. By creditors’ own calculations, Spain faces 27 binding awards worth more than €2.3 billion across all jurisdictions.
In the United States alone, judgments against the country come to around €700 million. They stem from retroactive cuts to renewable energy subsidies brought in from 2013, under the government of former prime minister Mariano Rajoy.
FROM GREEN CHAMPION TO MOST-SUED STATE
Spain spent the 2000s courting foreign capital with generous subsidies for solar and wind power, including guaranteed tariffs that promised investors a fixed return. The incentives drew an estimated €13 billion into Spanish renewables, according to industry figures, making the country one of Europe’s largest markets for green energy.
The 2008 financial crisis changed that calculation.
Faced with a ballooning deficit in its electricity system, Madrid began unwinding those incentives, a process that culminated in sweeping reforms in 2013 and 2014. Investors who had put money into Spanish renewables said the changes wrecked the value of their projects.
Dozens went to arbitration, arguing the cuts breached the Energy Charter Treaty (ECT), an international accord protecting cross-border energy investment. The flood of claims turned Spain into one of the most-sued countries under the treaty.
The United States became a central battleground in August 2024, when the District of Columbia Circuit appeals court ruled that American courts could hear cases to enforce the awards. Spain’s plea to the Supreme Court was its last attempt to overturn that finding.
Spain countered that US federal courts had no jurisdiction to hear the cases. It argued that, because European Union law bars arbitration between an EU investor and an EU government, it had never been able to agree to arbitrate in the first place.
BRUSSELS LINES UP BEHIND MADRID
That argument leaned on the European Union’s own courts. The European Court of Justice (ECJ) has ruled, in its Achmea and Komstroy judgments, that arbitration between member states and investors from other member states is incompatible with EU law.
The European Commission has pressed the same line. In March 2025 it ruled that paying one such award, worth €101 million and owed to the investment group Antin, would amount to illegal state aid.
The Commission found the payment “incompatible with the internal market” and ordered Spain neither to pay it nor to let it be enforced. The ruling cast Brussels in the unusual role of helping a member state sidestep a binding international award.
The European Union, along with Poland, Romania and Bulgaria, had urged the justices to take the case up. Those member states argued that awards between EU investors and governments are invalid under EU law, and warned they could face similar enforcement actions of their own.
Washington took the other side. The US government, through its solicitor general, recommended that the court reject the appeal, a step it duly took.
ASSETS IN THE FIRING LINE
Creditors called the outcome a significant victory for investors hit by the regulatory changes. They are pursuing Spain in several other countries, including Belgium, the Netherlands, Australia, Singapore and the United Kingdom.
In Belgium, creditors have frozen around €250 million held in Spanish bank accounts. In the Netherlands, a court has cleared the way to seize and sell the building that houses the Instituto Cervantes, Spain’s state cultural centre, in Utrecht.
Australian courts have recognised a series of awards against Spain worth more than €400 million between them. Singapore’s highest court has also ruled in creditors’ favour in cases covering more than €300 million.
The Spanish Government said the US decision did not end the enforcement proceedings. It said it would keep opposing recognition of the awards on substantive grounds under EU law, the latest in a string of legal battles shadowing the administration of Prime Minister Pedro Sánchez.
For investors, the result reinforced a principle they have pressed for years: that binding arbitration awards must be honoured, whatever the regulatory about-turn that produced them. Spain’s blanket refusal to comply has drawn repeated criticism from investors and legal scholars.
The case also sharpened a wider clash between two legal orders. International arbitration treats the awards as final, while the EU insists its own law overrides them, leaving creditors to chase Spanish assets wherever they can find them.
