The highest court of the European Union ruled today that an EU mandate for dragnet surveillance of travelers through government access to airline reservations might be permissible under EU law — but only under conditions that governments of EU member countries, and the US government, may be unable or unwilling to meet.

In 2016, the EU enacted a directive requiring each EU member state to enact a law requiring airlines to hand over copies of passenger name records (PNRs) to the government, and establish a new surveillance agency to profile travelers based on this PNR data.  This EU PNR Directive was modeled on US law and on the extrajudicial practices — never tested against the provisions of international human rights treaties, which generally can’t be invoked in US courts — of the US Department of Homeland Security.

The Belgian “Ligue des droits humains” (LDH) filed a lawsuit in the Belgian Constitutional Court challenging the law enacted in Belgium to implement the EU PNR Directive as contrary to multiple provisions of Belgian and EU law.

Before deciding the questions of Belgian law, the Belgian court requested a preliminary ruling from the Court of Justice of the European Union (CJEU), the highest EU court, as to whether the EU PNR Directive is consistent with fundamental EU human rights law.

In today’s ruling (press release and summary in English, full text of judgment in French, provisional translation of judgment in English), the CJEU finds that the EU PNR Directive is not, on its face, invalid — but only if it is implemented and applied in accordance with a long list of conditions specified by the CJEU in its decision.

Governments of EU member states may be unable or unwilling to comply with all of those conditions.

The decision by the CJEU addresses the implications and validity of the EU PNR Directive both as a mandate for suspicionless dragnet surveillance and as a mandate for control of travel, in which PNR data is used as the basis for profiling and other actions.

Of the many conditions set by the CJEU, we find this one on secret law, secret evidence, and judicial review among the most significant. According to the court’s press release:

[T]he Court also stresses that the competent authorities must ensure that the person concerned can  understand the operation of the pre–determined assessment criteria and programs applying those criteria, so that it is possible for that person to decide with full knowledge of the relevant facts whether or not to exercise his or her right to judicial redress. Similarly, in the context of such an action, the court responsible for reviewing the legality of the decision adopted by the competent authorities as well as, except in the case of threats to State security, the persons concerned themselves must have had an opportunity to examine both all the grounds and the evidence on the basis of which the decision was taken, including the pre–determined assessment criteria and the operation of the programs applying those criteria.

In cases where EU governments act on “recommendations” from the US government to restrict travel to, from, or within the EU, the EU authorities nominally responsible for these actions may not know what evidence (if any) or algorithms for the basis for US recommendations. And the US may not be willing to share that information with EU governments, especially if EU law might require EU governments to disclose that information to European judges, much less to individuals who are “targeted” on the basis of US recommendations.

The court case now returns to the Belgian courts, but it  seems likely that changes to the laws implementing the EU PNR Directive in Belgium and most if not all other EU member states will be required to conform these laws to the conditions laid down today by the CJEU. Another round of litigation in EU member states and perhaps again in the CJEU is likely to be needed to determine whether amended laws have met those tests. Stay tuned!