The Grand Chamber of the European Court of Human Rights (ECHR) agreed Monday to hear a challenge to the bulk data surveillance regime employed by UK intelligence agencies.

A lower chamber of the court ruled in September that the UK’s surveillance practices violated human rights law but ruled that the process of bulk data collection itself did not violate the European Convention on Human Rights. Now, the groups behind the challenge are seeking a definitive ruling against bulk collection from the ECHR’s highest chamber. The civil and digital groups and charities include Liberty, Privacy International and Amnesty International.

In the September hearing, the lower chamber of the court ruled that the data collection (or interception) regime violated European Convention on Human Rights Article 8 (the right to respect for private and family life/communications) and Article 10 (the right to freedom of expression and information).

However, the lower chamber declined to call the regime unlawful on the grounds of being “general and indiscriminate” retention of data. The groups behind the new challenge argue that the lower chamber dd not go far enough, and that an overarching judgment is needed to fundamentally change the way the UK approaches the collection and surveillance of personal data.

Caroline Wilson Palow, general counsel at Privacy International, called on the court to “reject these mass surveillance practices and find that they are fundamentally incompatible with the rights to privacy and freedom of expression enshrined in the European Convention on Human Rights.”

The future of the challenge is uncertain, as the wait for a hearing from the Grand Chamber could take several years. In addition, it is uncertain whether the UK will still be party to the ECHR by that time given the country’s efforts to exit the EU. While the ECHR is separate from the EU, some in the UK’s Conservative party have advocated pulling out of the Convention in addition.