Members of the Christian sect are renowned for their door-to-door campaigns, often logging religious affiliations and other details about those they visit. Today, the European Court of Justice will decide whether this practice complies with the EU’s new data-protection laws. Jehovah’s Witnesses brought the case after a Finnish data-protection commission ruled that it, like companies, could not store people’s details without their consent. The sect says its door-knockers operate as individuals; the ECJ’s advocate-general Paolo Mengozzi disagrees. He cites the movement’s distribution of printed note-gathering forms to members as proof it is centrally organised. An unfavourable ruling would be another blow. In Russia Jehovah’s Witnesses are designated an extremist group. Last year the Russian Supreme Court banned all its organisations—a measure enforced through severe harassment, reckons Human Rights Watch, an NGO. With data laws now casting doubt over its methods in Europe, members fear doors will slam ever harder in their faces.