EU countries should be allowed to log telecommunications data for law enforcement purposes as long as they put "strict" safeguards in place, an adviser to the bloc's top court recommended Tuesday.
Privacy and data retention is a highly sensitive issue in Europe, which flared up after revelations in 2013 of wide-scale surveillance by US intelligence services.
The European Union had in 2006 mandated the retention of private phone and internet data - such as the location, time and frequency of communications between individuals - as part of anti-terrorism measures adopted after attacks in Madrid and London.
But the European Court of Justice struck down the law in 2014, finding that it breached citizens' fundamental rights. The top court has now been asked by judges in Britain and Sweden for clarification on whether an EU country can put in place a general obligation for providers of electronic communication services to retain data.
Henrik Saugmandsgaard Oe - one of 10 advocates general who provide legal opinions to the EU court - weighed in on the matter Tuesday.
Saugmandsgaard Oe believes that a general data retention obligation "may be compatible with EU law" as long as it meets certain criteria, the court said in a statement.
The judges generally follow the advocate generals' advice.
The obligation must be in line with the respect for private life and the right to data protection, "strictly necessary" for the fight against "serious crime" and "proportionate," Saugmandsgaard Oe found.
He also recommended that it be "laid down by legislative or regulatory measures possessing the characteristics of accessibility, foreseeability and adequate protection against arbitrary interference," the Luxembourg court said.
Its final ruling on the matter is likely to take several more months.