Laws surrounding online surveillance will always prove controversial, and this is certainly true of the UK's proposed Investigatory Powers Bill - aka the Snooper's Charter.
Currently in draft form, the final content and scope of the bill could be set today as the European Court of Justice rules on a challenge brought against the existing Data Retention and Investigatory Powers Act 2014 (Dripa).
The case has the support of many European states, and the outcome of the case will determine the powers of data collection the UK government is able to exercise. It is expected that the case could be one of the deciding factors in the in-out referendum in June when the UK votes on whether to remain part of Europe or to go it alone.
15 judges in Luxembourg are due to rule on the legality of Dripa which was rushed through parliament; it has already been determined that the Act is at odds with EU law. Specifically, it is said that the Act goes against Article 8 of the European convention on human rights, the right to respect for private and family life, and Articles 7 and 8 of the EU charter of fundamental rights, respect for private and family life and protection of personal data.
The fact that the UK government's proposed gathering of data about all internet users - not just those under investigation in cases - is likely to be central to the decision and future direction of surveillance laws. Because rulings by the European Court of Justice must also be applied to UK law. Ultimately it could mean that the Investigatory Powers Bill needs to be rewritten.
Unsurprisingly, privacy groups are far from happy with both Dripa and the Snooper's Charter. Camilla Graham Wood from Privacy International, said: "The UK, in enacting legislation that is almost identical to the European data retention directive which the [ECJ] ruled unlawful, is mandating data retention on a widespread, indiscriminate and untargeted basis.
"Such a broad and wholesale retention of communications data is in violation of European law. The effect of Dripa is to use bulk data retention to create a dossier on every person in the UK. It includes every internet and mobile phone transaction you undertake, every location will be filed, every meeting noted, every website indexed and every call marked.
"Blanket retention of communications data, without suspicion, creates a honeypot of information for criminals and hackers, and this case will have implications for personal privacy and the security of individual personal data.