Privacy International has appealed to the High Court to strike down a key part of the Investigatory Powers Bill that allows the government to issue blanket hacking warrants to GCHQ.

The so-called "thematic warrants" contained in the so-called Snooper's Charter allow the spy agency to hack into the computers and phones of people both inside and outside the UK.

Unlike normal warrants, they do not require a single target to be named and can instead be used to cover an entire class of unnamed property or persons, such as "all mobile phones in Nottingham" in the example given by the campaign group.

Privacy International initially raised a complaint about these general warrants in 2014, when it took its case to the Investigatory Powers Tribunal (IPT), which oversees agencies including GCHQ.

The campaign group had argued that such blanket warrants have no basis in UK law and also violate Articles 8 and 10 of the European Convention on Human Rights (ECHR) - the rights to privacy and freedon of speech. However, the IPT ruled in favour of the government in February this year.

Consequently, the organisation has taken its case to the High Court, seeking to overturn the IPT's ruling. As well as its claims that thematic warrants violate the ECHR, the group is also claiming that it undermines 250 years of English common law, which it claimed "has long rejected general warrants".