(Telecompaper) A general requirement for operators to retain certain communications data is permissible in the EU in order to fight serious crime, according to an opinion from the European Court of Justice's advocate general, Henrik Saugmandsgaard Oe. However, any such requirement must be subject to strict limits, including protecting the fundamental rights of and protection of personal data, as earlier decided by the Court when it struck down in 2014 the EU's data retention directive. The opinion was issued at the request of courts in in Sweden and the UK, where appeals were filed against national legislation on data retention. The AG's opinion is not binding, and the EU court must still take a final decision in the case before it goes back to the national courts.