The Court of Justice of the EU on Thursday annulled the European Parliament’s 2021 decision to strip Catalan separatist lawmakers’ immunity, citing doubts regarding the impartiality of the process through which the measure was adopted.

Following the illegal Catalan independence referendum in 2017, former regional President Carles Puigdemont and separatist politicians Toni Comín and Clara Ponsatí fled to Belgium. Spanish authorities eventually charged all three with alleged offenses of insurgency and misappropriation of public funds, and issued warrants for their arrest, but Belgian judges declined to extradite them.

The Catalan politicians’ ability to evade Spain’s efforts to detain them appeared to be reinforced in 2019, when all three were elected to the European Parliament and gained the right to claim immunity as lawmakers. Madrid pushed to stop the MEPs-elect from being recognized by the Parliament, arguing their election could only be certified if they returned to Spain and swore allegiance to the constitution, but the separatists were ultimately admitted by the legislature’s then-president, David Sassoli, in 2020.

Spain then petitioned the Parliament to lift the separatists’ immunity, and in 2021 a majority of lawmakers voted in favor of doing so. Although Puigdemont, Comín and Ponsatí challenged that waiver, the EU’s General Court upheld it in 2023, weakening their ability to evade Madrid’s extradition requests.

But Thursday’s appeals ruling by the top court annuls the Parliament’s decision, finding the institution failed to “ensure the impartiality” of the procedure to waive the lawmakers’ immunity. The high court’s doubts regarding the neutrality of the process focused on Spain’s far-right Vox party, which was involved in filing the criminal case at the origin of Madrid’s extradition request.

The court found that the Parliament violated the principles of impartiality by permitting former Bulgarian MEP Angel Dzhambazki, whose European Conservatives and Reformists Group then included the Vox party, to serve as the rapporteur overseeing Spain’s waiver request in the Legal Affairs Committee. EU law establishes that examinations of petitions of this kind cannot be led by lawmakers connected to the prosecution.

As additional evidence of Dzhambazki’s lack of impartiality, the ruling notes that the Bulgarian lawmaker participated in a 2019 event titled “Catalonia is Spain,” at which the Vox party’s secretary-general declared, “Long live Spain, long live Europe and lock Puigdemont up!”

In addition to having its 2021 decision annulled, the Parliament is ordered to pay the legal costs incurred by Puigdemont, Comín and Ponsatí in their initial challenge before the EU’s General Court, and their appeal to the Court of Justice. The ruling represents a stark rebuke of the Parliament and its handling of the Catalan separatist saga. The Parliament declined POLITICO’s request for comment.

Of the lawmakers involved in the case, only Comín remains a member of the EU legislature. Ponsatí returned to Spain in 2023 and was briefly detained before being released by authorities.

Puigdemont remains in Belgium, awaiting the implementation of a controversial amnesty law passed by the Spanish parliament in 2024. The legislation’s application has been halted by the courts, with the separatist leader specifically blocked from benefiting from the law due to pending embezzlement charges.

Spain’s Constitutional Court last week rejected a request to suspend Puigdemont’s arrest warrant. The same body is expected to rule on whether he should benefit from the amnesty bill later this year.

Sebastian Starcevic contributed to this report.