Last week, the former Catalan president, Carles Puigdemont, was remanded in custody by a court in Germany pending a decision on whether to extradite him to Spain to face charges of rebellion, sedition and misuse of public funds in relation to the referendum and subsequent declaration of independence in Catalonia.

Puigdemont's extradition is being sought via a European Arrest Warrant, the EU's flagship crime-fighting measure, a fast-track extradition regime through which an arrest warrant issued in one EU country is given effect in another.

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Anyone who cares about justice in the EU should be wary of the situation facing Puigdemont today.

How he came to be arrested and detained in Germany says much about the future of the "area of freedom, security and justice" established in the EU in the 1997 Treaty of Amsterdam.

The European area of freedom, security and justice grew out of the need to guarantee the 'four freedoms' of Europe: the freedom of movement of goods, capital, services and people within the EU.

In order to protect citizens and safeguard their freedoms, the need arose to break down barriers and disparities between EU member states with regard to internal security, the fight against crime, and the rights guaranteed to people moving from one country to another.

At heart, the concept is that people should not be able to escape justice by simply moving across European borders; but equally they should expect their rights to be similarly respected no matter where in Europe they are.

Puigdemont's arrest in Germany under a European Arrest Warrant challenges those principles to their very core.

This was not the first time that a European Arrest Warrant had been issued by Spain for Puigdemont.

Puigdemont was arrested in Belgium on an near-identical European Arrest Warrant in November.

Belgian impasse

The case spent weeks in litigation before the Belgian courts, with his lawyers arguing that his human rights, including his right to a fair trial, would be violated if he were surrendered to Spain, that the crimes that he was being accused of had no corresponding basis in Belgian law (a necessary pre-condition to extradition), and that the arrest warrant was merely another tool being used by the Spanish authorities to crack down on people advocating for the independence of Catalonia.

The Belgian courts were not given the chance to rule on these issues, however.

Once it became clear that the Belgian courts were not going to blindly execute the arrest warrant, the Spanish Supreme Court ordered it withdrawn.

The decision was based in large part on the Spanish court's reluctance to have Belgian courts looking into the situation in Spain or perhaps worse, deciding to refuse the request.

In essence, the court did not want the Belgian courts to look through Spain's dirty laundry.

And they got their wish: the Belgian courts did not rule on Puigdemont's arguments, he was released and settled down into a house and life in the Brussels suburbs.

On 23 March, however, a new European Arrest Warrant was issued by Spain related to Puigdemont and others based on the very same charges.

Puigdemont was in Finland at the time. According to reports, upon learning of the new arrest warrant, he immediately sought to return home to Belgium.

But he was being followed by the Spanish intelligence service during his drive back home.

Upon his crossing from Denmark into Germany – a country which has crimes similar to those he has been accused of in Spain – the intelligence agents reportedly alerted the German authorities to his presence in the country and he was arrested there.

Quite why Puigdemont was not arrested in Finland or Denmark on his way back to Belgium, or indeed left to return home to Belgium to reopen the proceedings there, is unknown.

But given the reasons for the withdrawal of the original arrest warrant, the timing of its re-issuance, and the reported presence and proactive approach of the Spanish intelligence service, the impression that is left is that arrest in Germany, a country through which Puigdemont was merely transiting, was a strategic choice.

There are no rules within the European Arrest Warrant system preventing countries from strategically withdrawing and then reissuing arrest warrants at more convenient times, in more convenient places.

But perhaps there should be.

Puigdemont's case sets a dangerous precedent that runs directly contrary to the goal of the European area of freedom, justice and security that EU citizens should expect to be treated equally throughout the Union.

Gaming the European Arrest Warrant?

It creates the possibility that the European Arrest Warrant can be used as a threat, preventing EU citizens exercising their rights of freedom of movement, issued wherever extradition is most likely, but withdrawn if the court does not appear to be finding in the government's favour, thus preventing the subject's rights from being protected and enforced by a court of law.

With the rise of governments across Europe that are increasingly hostile to independent voices – notably in Poland and Hungary where an independent judiciary and civil society are under attack respectively – the prospect of a European Arrest Warrant system that can be gamed for political or strategic purposes like this should be avoided at all costs.

Since its founding, we at Fair Trials have been advocating for fairer cross-border criminal justice cooperation mechanisms.

We are firmly of the belief that such mechanisms must respect human rights, be free of politicisation and subject to the rule of law in order to be efficient and effective.

We have long argued that improved human rights safeguards are needed in the European Arrest Warrant system in order to increase the level of trust that the countries of the EU have in each other's criminal justice systems and, thus, to ease the process of extradition.

Such considerations are at the very heart of the European area of freedom, security and justice for which Puigdemont's case marks a worrying new chapter.

Ralph Bunche is the Europe director of Fair Trials, a global justice watchdog