Transnational Criminal Proceedings in Spain: European Arrest Warrant, Mutual Legal Assistance and Cross-Border Defence

Crime no longer respects borders, and neither does the criminal response. When the evidence sits on a server in another country, the funds have been moved across several jurisdictions, or the investigated person lives abroad, the case stops being purely national and enters the field of international judicial cooperation in criminal matters. This is a technical area, with its own deadlines, specific instruments and safeguards that the defence must monitor closely. As a firm that assists in transnational criminal proceedings, in this guide we explain how those mechanisms work and where the room for defence lies.

What a Transnational Criminal Case Is

A case is transnational when one of its essential elements is located outside Spain: the investigated person (who lives in or has fled to another country), the evidence (documents, data, communications or witnesses abroad) or the assets that must be secured or confiscated. In these situations, the Spanish court cannot act directly on the territory of another State: it needs the cooperation of the authorities of the country where that element is found.

The legal framework for that cooperation is not in the Criminal Code (CP) —which defines offences— but in a web of European Union legislation and international instruments: framework decisions, EU regulations, Council of Europe conventions and bilateral treaties. Knowing that framework is decisive, because each instrument sets its own deadlines, requirements and grounds of opposition.

The European Arrest Warrant (EAW)

The European Arrest Warrant (EAW) is the flagship instrument within the European Union. It allows the judicial authority of one State to request the arrest and surrender of a person found in another Member State, whether to prosecute them or to enforce a sentence already imposed. It is governed by Framework Decision 2002/584/JHA, transposed in Spain by Law 23/2014 on the mutual recognition of criminal decisions in the European Union.

Its great advantage is speed. Unlike the slowness of traditional extradition, the EAW rests on the principle of mutual recognition: the authority of the executing State does not review the merits of the accusation, but checks that the formal requirements are met and that no ground for refusal applies. As a rule, the decision on surrender must be taken within sixty days, extendable by a further thirty, giving a maximum of ninety days.

In addition, for a closed list of serious offences —terrorism, human trafficking, drug trafficking, corruption, money laundering and others— the double-criminality check is removed: it is not necessary for the act to be an offence in both States under the same label. For all other conduct, that requirement still applies.

Grounds for Refusing Surrender

Receiving an EAW does not mean that surrender is automatic. Law 23/2014 distinguishes two sets of grounds on which the Spanish authority may or must refuse it, and that is where much of the defence is concentrated:

• Mandatory grounds for refusal: res judicata or ne bis in idem (the person has already been tried for the same facts), limitation of the offence or the sentence under Spanish law where Spain has jurisdiction, pardon or amnesty, and being below the age of criminal responsibility.
• Optional grounds for refusal: the principle of territoriality (acts committed in Spain), the lack of double criminality for offences not on the closed list, or the requested person being a Spanish national or resident who undertakes to serve the sentence in Spain.

To these grounds is added a safeguard of the first order developed by case law: surrender may be refused where there is a real risk of inhuman or degrading treatment due to detention conditions in the issuing State. The defence can submit reports on the prison system of the destination country to trigger this scrutiny and demand additional guarantees before any surrender.

Letters Rogatory and Mutual Legal Assistance

Where what is needed is not a person but evidence located abroad, the route is the letter rogatory or, in its broader name, mutual legal assistance in criminal matters. Through it, one judicial authority asks another to carry out a step on its territory: taking a witness statement, obtaining banking records, searching premises or intercepting communications.

The legal framework is dense. In the European sphere, the 1959 Council of Europe Convention on mutual assistance in criminal matters and its 2001 Protocol operate alongside the 2000 European Union Convention on mutual legal assistance. Towards third countries, recourse is had to the bilateral mutual legal assistance treaties (MLATs) signed with States such as the United States, Mexico or Morocco.

The critical point for the defence is the lawfulness of the evidence. Evidence obtained abroad is not incorporated automatically into the Spanish proceedings: it must have been gathered in compliance with the essential procedural safeguards of our legal system. If an interception of communications or a search was carried out without judicial oversight equivalent to that required in Spain, the defence can challenge its validity and seek its exclusion.

Asset Recovery and Cross-Border Confiscation

In economic crime and money laundering, money rarely stays still. Cooperation therefore includes mechanisms to locate, freeze and confiscate assets situated in other States. Within the European Union, Regulation (EU) 2018/1805 on the mutual recognition of freezing and confiscation orders establishes a swift system: a freezing order issued in one State must be enforced in another with great speed, within deadlines that can be around forty-eight hours for the most urgent measures.

Outside the European area, asset recovery relies on international conventions and on initiatives such as the World Bank's StAR programme for the recovery of stolen assets. For the defence, this terrain requires monitoring the proportionality of the precautionary measures, the lawful origin of the affected assets, and the rights of bona fide third parties who may be caught up in a freezing order.

Eurojust and Joint Investigation Teams

Cooperation is not limited to one-off requests between authorities. The European Union has Eurojust, the agency that coordinates and facilitates cooperation between national judicial authorities in cases of serious cross-border crime, and Joint Investigation Teams (JITs), in which authorities from two or more States work in an integrated way on the same case for a set period.

For the investigated person, these structures mean that several countries may be sharing information and coordinating steps simultaneously. The defence must understand who is directing the investigation, what information is being exchanged and under what safeguards, so that the investigated person's rights are not diluted in action spread across jurisdictions.

International Ne Bis in Idem and Jurisdiction Conflicts

One of the most serious risks in transnational proceedings is double prosecution: that two States seek to try the same person for the same facts. The principle that prevents this is ne bis in idem, guaranteed in the European area by Article 50 of the Charter of Fundamental Rights of the European Union and Articles 54 to 58 of the Convention implementing the Schengen Agreement.

When several States claim jurisdiction over the same facts, a positive conflict of jurisdiction arises that must be resolved to determine where the matter is tried. The defence can invoke ne bis in idem to halt a second set of proceedings for facts already tried —or already closed with the force of res judicata— in another State, and to prevent the person from being exposed to cumulative sanctions. It is one of the most powerful tools in defence in transnational proceedings.

EAW Versus Classic Extradition

The EAW should not be confused with classic extradition. They are two different worlds:

• Scope: the EAW operates only between European Union States; extradition is used towards third countries.
• Procedure: the EAW is entirely judicial; extradition goes through a dual phase, judicial and governmental, which in Spain is heard before the National High Court (Audiencia Nacional) with a final intervention by the Government.
• Deadlines: the EAW is resolved within a maximum of ninety days; classic extradition can take between six and eighteen months, or longer.

This distinction matters from the first minute, because it determines which safeguards are triggered, which authority decides and which deadlines the defence will be working with. The strategy against an EAW is not the same as against an extradition request from a non-European country.

What the Defence Offers in a Transnational Case

The defence in these proceedings does not improvise: it monitors every cog of the cooperation mechanism. Its contribution takes shape on several fronts:

• Control of the deadlines and formal requirements of the EAW or the extradition request, raising the applicable grounds for refusal.
• Challenging the evidence obtained abroad where it was gathered without the essential safeguards of Spanish proceedings.
• Triggering ne bis in idem and resolving conflicts of jurisdiction to prevent double prosecution.
• Defence against cross-border confiscation and freezing, protecting the lawful origin of the assets and the rights of third parties.
• Coordination with lawyers in other jurisdictions, so that the strategy is coherent across all the States involved.

In this field, the settled case law of the Spanish Supreme Court and the doctrine of the Court of Justice of the European Union on mutual recognition, detention conditions and ne bis in idem set the terrain on which any strategy operates. Knowing that framework makes it possible to anticipate the outcome of each incident and to choose the most effective route of opposition.

Transnational Criminal Defence in Madrid and Throughout Spain

The criminal law firm Alonso Sala, based at Calle Velázquez 27 in Madrid and with coverage throughout Spain, assists individuals and companies caught up in criminal proceedings with an international dimension: European Arrest Warrants, extradition requests, letters rogatory, cross-border confiscation and conflicts of jurisdiction. We work on controlling the deadlines and the grounds for refusal, challenging evidence obtained abroad and coordinating with the defence in other jurisdictions, always with the safeguarding of the investigated person's rights as the priority.