A message at the Place de la Bourse following Tuesday’s attacks in Brussels, Belgium. At least 31 people are thought to have been killed when Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Carl Court/Getty Images)

The terrorist attacks in Paris and Brussels highlight an important dilemma for the European Union. Over the past two decades, the E.U. has made it much easier for people to travel across borders, especially among countries which had signed the Schengen agreement.

However, the E.U. has not created very comprehensive arrangements for police cooperation, which might allow the police to tackle cross-border crime, including terrorism. In the early part of the last century, the U.S. faced increased challenges from criminals using cars to travel from one jurisdiction to another. This helped build a case for expanding the role of the FBI and other federal institutions.

Europe faces similar challenges, but doesn’t have an FBI. Here’s why.

Countries find it hard to cooperate over policing

National policing activities are often highly sensitive because they are so closely tied with the notion of state sovereignty. Max Weber famously defined the state as the organization that had a monopoly on legitimate violence in a given territory. In other words, the sovereign state is the organization that is able to use violence to enforce its rules and have its violence accepted as legitimate by its population. When states cooperate over policing matters, they are pooling a key aspect of sovereign power and, in effect, weakening their control over violence.

The European Union is still an organization composed of independent states rather than a true federal system. Its constituent states have been happy to cooperate over economic matters, and even many social issues, but have been reluctant to give up control over policing. Over time, they have started cooperating more on policing matters, but slowly and reluctantly.

Many of the most difficult problems in the negotiations over Schengen involved policing questions, such as whether police engaged in “hot pursuit” could pursue a suspect over state borders.

The result is weak policing cooperation

States’ unwillingness to cooperate over policing has led to a set of relatively weak institutions. Perhaps the most important is Europol, which was only relatively recently integrated into the full European Union framework. Europol is not a real policing agency – instead, it helps foster cooperation, and has increasingly grown to provide independent information and analysis capacities to national police forces, as well as coordinating information-sharing with the U.S.

Other domestic intelligence and policing arrangements – such as the so called TREVI Group and the Police Working Group on Terrorism – are less formal institutions than informal clubs in which officials can coordinate and share information. EUROJUST helps European prosecutors to coordinate – but again it has no real independent powers.

What Europe does not have is any cross-national agency with the power to carry out its own investigation and make its own arrests.

This means that cross-border policing in the European Union has big holes. It depends heavily on informal cooperation rather than formal institutions with independent authority. Sometimes this works reasonably well. Sometimes this works particularly badly. Belgium is a notorious problem case, because its policing arrangements are heavily localized. In the past, many Belgian policing forces have had difficulty cooperating with each other, let alone with other European forces.

All this said, the U.S. also has had problems with the stove-piping of information, as the September 11 Commission report emphasized at length. Its response to these problems – including increased information sharing between intelligence services and justice agencies, and “fusion centers” to coordinate between different levels of policing and security – have drawn strong criticisms on privacy grounds.

While terrorist attacks may spur change in Europe, they are unlikely to lead to wide-scale reform

For sure, terrorist attacks have sounded a wake-up call for European policing forces. However, the most plausible paths of reform involve national institutions rather than any cross-national policing force. National institutions are very sticky and hard to change, and states resist new institutions that could really trespass on their internal sovereignty.

To take a different example, immigration and refugees present an even bigger and more visible set of challenges to the E.U. than terrorism, yet the E.U. has been unable to agree on reforms that might expand the budget and powers of FRONTEX, the E.U. agency charged with coordinating border control. Creating a European FBI-style institution would be an even bigger lift.

What is likely to happen is that the E.U. will do more of what it is already doing – building and deepening cooperation arrangements between national policing and domestic security agencies. Legislation in the works to share information on airline passengers is likely to be accelerated. However, the E.U. will likely continue to build privacy protections into these new rules – under recent legislation, privacy officials have increased power, and will be willing to press for better privacy as the price for better cooperation.