Toulouse: Advocate General Maciej Szpunar handed the Court of Justice a fresh set of criteria on 3 September for judging whether national data retention laws survive contact with EU law. The opinion does not bind the judges. It does tell every interior ministry in the Union which arguments still work and which ones the Court’s own case law has quietly retired.

Europe has been arguing about data retention for more than a decade. The Court struck down the original Data Retention Directive in 2014, then spent years explaining what member states could keep instead. Blanket, untargeted storage of traffic and location data failed each time. Targeted retention, tied to a place, a group or a serious-crime threshold, survived. National legislators read those rulings selectively, and prosecutors kept using data that domestic courts later called unlawful.

Szpunar’s opinion tackles that gap directly. He sets out how a referring judge should test necessity and proportionality rather than accepting a government’s assurance that investigators need everything. The practical effect falls on IP address retention, which police forces across the Union treat as the single most useful category, and on the question of who authorises access once the data exists. An independent authority, not the investigating officer, remains the benchmark.

Interior ministries will not enjoy the reading. Several capitals rewrote their retention statutes after 2022 and assumed the matter closed. A judgment that tightens the necessity test would reopen legislation in France, Belgium, Germany and Spain at the same moment the Commission is preparing its own proposal on lawful access to data. Officials working on that file have argued that fragmented national rules justify an EU instrument. A strict ruling strengthens their case while narrowing what the instrument can contain.

There is a serious argument on the other side. Serious crime investigations, particularly those involving child sexual abuse material and organised drug trafficking, often begin with a subscriber lookup that only retained data makes possible. Police associations point out that targeted retention presumes investigators already know where to look, which is rarely true at the start of a case. That objection has never persuaded the Court, but it has persuaded enough national parliaments to keep producing laws that end up in Luxembourg.

The Court follows its advocates general in most cases, though not all, and the Grand Chamber takes its time on files this sensitive. A judgment before late 2027 would count as quick by the standards of this saga. Until then national judges have a clearer map of the terrain, and defence lawyers have a new citation.

Anyone tracking the file can read the Court’s own summaries through its press release archive, and the Union’s overview of Charter protection sits on the European e-Justice Portal. Both matter more than the political commentary, because the Court decides this one on its own terms.