On Thursday 27 April, the European Court of Justice decided that the legal authorities or jurisdictions of a member state cannot refuse to recognise an A1 certificate (former E101 formula) awarded by another member or associated state as long as the certificate has not been withdrawn or declared invalid.
In the preliminary ruling before the European judges (C-620/15), the French authorities contested the validity of this certificate (attesting that a foreign worker active in a member state...