Extradition from Spain to the United States: Process and Grounds for Refusal

For clients with ties to the United States, one of the most common questions is whether a request from US authorities is handled the same way as a case within the European Union. It is not. The European Arrest Warrant is an EU-internal instrument and does not apply to the United States. Surrender between Spain and the US follows the older, more traditional route of classic extradition, based on a bilateral treaty and, since Spain's accession to the EU framework, also shaped by an EU-level agreement with Washington. This guide explains, in general terms, how that process works and what can be argued against it.

The Legal Framework: The Bilateral Treaty and the EU-US Agreement

The core instrument is the Extradition Treaty between Spain and the United States, signed in Madrid on 29 May 1970, which entered into force the following year and has since been updated by a series of supplementary treaties agreed over subsequent decades. That bilateral framework was later joined by the EU-US Extradition Agreement of 2003, a European Union-level instrument that supplements and, on certain specific points, modifies the individual bilateral treaties that EU member states — including Spain — have with the United States. In practice, this means an extradition case between Spain and the US is assessed against both layers: the long-standing bilateral treaty and the more recent EU-wide agreement that sits alongside it. It is a materially different legal architecture from the European Arrest Warrant, which does away with bilateral treaties altogether between EU states.

How the Request Reaches Spain

Because this is not an EU mutual-recognition mechanism, an American extradition request does not travel directly between judicial authorities. It is channeled through diplomatic routes — typically via the US Embassy and the Spanish Ministry of Justice — before reaching the courts. Once formalized, the case falls within the jurisdiction of the Criminal Chamber of the National Court (Audiencia Nacional), the specialized court that handles extradition matters in Spain. The requested person has the right to be informed of the request, to be assisted by a lawyer of their choosing or a court-appointed one, and to a hearing where the extradition's legal admissibility is examined. As in other extradition cases, the court also decides on the person's situation while the matter is pending — whether they remain in custody or are released under precautionary measures — a decision that depends heavily on individual ties to Spain and flight risk.

Grounds for Opposing Surrender

Classic extradition allows a broader catalogue of arguments than the EAW's narrow, exhaustively listed grounds. Depending on the specifics of the request, the defence may raise:

• Lack of dual criminality: the conduct described must be an offence under both US and Spanish law. Where the underlying facts do not correspond to any Spanish criminal offence, extradition should not proceed for that charge.
• Prescription (statute of limitations) under Spanish law: if criminal liability for the alleged facts would already be time-barred under Spanish rules, that can operate as a bar to surrender.
• The political-offense exception: a traditional, though narrowly applied, ground in extradition treaties, subject to specific exceptions and limits under the applicable instruments.
• Risk of a disproportionate sentence or breach of fundamental rights: where surrender would expose the person to treatment or a sentence Spain considers incompatible with its own legal safeguards.

Not every ground will be available in every case, and each one requires its own factual and legal groundwork — comparative analysis of the offence, reconstruction of limitation periods, or documentation on the specific circumstances of the prosecution abroad.

The Death Penalty Question

One issue that recurs specifically in US-related cases, given that capital punishment remains available under the law of some US states and under federal law for certain offences, is the death penalty exception. It is a well-established principle, consistent with Spain's constitutional prohibition on capital punishment and its broader human-rights commitments, that Spain generally does not extradite a person to face a possible death sentence unless the requesting state provides adequate assurances that the death penalty will not be sought, imposed, or carried out. This is not a blanket refusal of all US extradition requests — the vast majority do not involve capital charges — but where the underlying offence could in principle carry a death sentence, this becomes a central point the defence will raise, and the kind of assurances offered by the requesting authorities is scrutinized carefully as part of the case.

A Longer, More Layered Procedure Than the EAW

Because extradition to a non-EU state combines a judicial phase before the National Court with a subsequent governmental phase — in which the Council of Ministers retains the final word on surrender — the overall timeline is typically considerably longer than an EAW case, and involves more procedural stages at which the defence can act. Anyone facing, or anticipating, a US extradition request benefits from early legal advice: identifying which grounds are realistically available, gathering the documentation each one requires, and understanding how the judicial and governmental phases interact are decisions best made from the very first contact with the case, not after the hearing has already been set. For the general mechanics of how the National Court examines extradition and European Arrest Warrant cases, see our overview of the European Arrest Warrant in Spain, and for the full list of treaties Spain has in force, our guide to Spain's extradition treaties.