Before the German Constitutional Court (the Court) it was claimed that the European Arrest Warrant and the implementing legislation was unconstitutional; that the wide waiver regarding dual criminality introduced foreign law to the domestic legal order (and thereby, legal uncertainty); and that the defendant had no specific right to judicial review enshrined in the extradition process.

The Court considered the arguments concerning the rights of citizens and extradition in particular in terms of Article 16.2 (the right against extradition) and Article 19.4 (access to justice) of the German 'Basic Law'. It also considered the purpose of the European Arrest Warrant and the Surrender Procedures between Member States and corollary tensions and issues arising from the principle of subsidiarity. The standard of review the court adopted was by way of an abstract review of norms,  it did not examine the factual details of the case.

The court noted the purpose of the Framework Decision (the Decision) was to introduce a simplified system for the surrender, as between judicial authorities, of convicted persons or suspects for the purpose of enforcing judgments or conducting criminal proceedings. It also recalled the purpose of Article 16.2 was to provide  the citizens' special association to the legal system that is established by them.

Innovative features of the Decision such as (limited) mutual recognition and double criminality were not discussed vis-a-vis the the facts of the case, however mutual recognition and double criminality of themselves as they appeared in the Decision  were not declared constitutionally unsafe, illegal or uncertain.  Under the Decision if the offences are punishable in the issuing Member State by a custodial sentence of at least three years, the following offences, among others, may give rise to surrender without verification  as to  double criminality: terrorism, trafficking in human beings, corruption, participation in a criminal organization, counterfeiting currency, murder, racism and xenophobia, rape, trafficking in stolen vehicles, and fraud, including that affecting the financial interests of the EU.  Among the charges listed in the request from Spain included terrorism and criminal organisation charges. The Court did not discuss in detail issues raised as to any equivalence of such charges under German law, but expert opinion was submitted that the point was moot as there existed similar crimes under German law on the facts (participating  in a criminal organisation and terrorism). This was disputed in a dissenting judgement.

On whole however Court considered the Framework Decision itself was valid as it gave sufficient margins to member states in introducing in its national implementing measure margins to reflect due process safeguards. For the most part the Court discussed the issues raised by the complainant in terms of the constitutional rights of German citizens and the development of co-operation for criminal law in the EU.  The Court in discussing questions of constitutionality, legality and legal certainty distinguished between three types of cases. Firstly it discussed cases involving a German citizen accused of offences committed partly or entirely on German territory. Here, the Court noted the Decision allowed Member States in their implementing measures to provide for the refusal of the execution in such situations – but Germany had not reflected this refusal despite Article 16.2 constitutionally enshrining a right against extradition. Accordingly in the Court’s view it would be disproportionate to allow extradition in this kind of situation.

Secondly where the action is developed in a foreign country, but the place of commission is within German territory. Here, a concrete consideration of the circumstances of each case would be necessary in order to find out whether extradition is proportionate. This must be a robust inquiry regarding a balancing of the issues and the Court believed that the implementing law did not reflect such balancing.

The third situation was one where there is a sufficiently significant link to a foreign country, or where the act is of a transnational nature. The Court did not have any legal concerns related to extradition of German citizens in this type of situation reasoning that whoever offends the laws of another legal system should be answerable to that system-  ‘all those who become part of such criminal structures cannot fully rely on their citizenship providing them protection from extradition’ in cases involving (for example) international terrorism or organised trafficking in drugs or human beings.

The Court also noted that the German law did not provide specifically for judicial control of the extradition. Stating this was also a basic constitutional right guaranteed by Article 19.4 (and recalling the objective of Article 16.2 was also to provide legal certainty) the Court condemned the national implementation measure as void and unconstitutional. The complainant could not be extradited on the basis of the legislation as it currently stood.