Former Catalan president Carles Puigdemont and four other ousted regional leaders turned themselves in to Belgian police on Sunday.
A spokesman for Belgian prosecutors said at a press conference that an investigative judge would decide by Monday morning whether Puigdemont should be detained, and would also consider whether to dismiss the European arrest warrant issued by a Spanish judge on Friday.
The five former members of the Catalan government face charges of rebellion, sedition and misuse of public funds related to a separatist push, including an October 1 independence referendum deemed illegal by Spanish authorities, and Catalan lawmakers voting to declare independence on October 27.
According to Belgian law, Puigdemont has the right to contest an extradition request at multiple levels in the courts. He could first appeal to a chambre du conseil, a low-level judicial body. If his argument were rejected there, he could then appeal to a chambre des mises accusation, which would have 15 days to reach a decision. If that chamber found against him, he could then make a final appeal to the cour de cassation, the highest appeal court. It would have a further 15 days to reach a decision.
If the highest court found in his favor, it would send the case back to another chambre des mises accusation. And if that court decided the extradition should go ahead, Puigdemont could appeal to the cour de cassation once again.
If Puigdemont decides not to raise legal objections, he could be transferred back to Spain within days.