The judges also found that there were insufficient safeguards put in place to govern access to communications data.
The judges ruled against the 16 complainants on the question of whether Britain further violated their privacy by sharing intelligence with foreign governments, saying that did not constitute a breach of their rights.
The judgement said: "While there is no evidence to suggest that the intelligence services are abusing their powers - on the contrary, the [then British watchdog] observed that the selection procedure was carefully and conscientiously undertaken by analysts, the court is not persuaded that the safeguards governing selection of bearers [internet cables] for interception and the selection of intercepted material for examination are sufficiently robust to provide adequate guarantees against abuse".
'The Court also held, by six votes to one, that: the regime for obtaining communications data from communications service providers violated Article 8 as it was not in accordance with the law; and that both the bulk interception regime and the regime for obtaining communications data from communications service providers violated Article 10 of the Convention as there were insufficient safeguards in respect of confidential journalistic material.More news: Kofi Annan Gave Me Sensitive Advice - Nana Addo
The UK's bulk interception powers, exposed by the whistleblower Edward Snowden, have been found to be illegal by the European Court of Human Rights.
They said Britain's activities - many of them run from GCHQ (Government Communications Headquarters), a vast intelligence gathering center in Cheltenham - could threaten the privacy of journalists, who may fear their contact lists or the websites they visit are being scrutinized by the government.
A tramway passes by the European Court of Human Rights on Aug.1, 2010, in the French city of Strasbourg.
After the judgment was published Snowden tweeted "for five long years, we have chased them through the doors of every court".More news: Jurgen Klopp fires back at Gary Neville
The UK's surveillance programs included Tempora, a computer system that stored data from all internet traffic; Karma Police, which recorded a browsing profile for all internet users; and Black Hole, a digital library of more than a trillion pieces of data including search histories, emails, and instant messages.
But Jim Killock of Open Rights Group - one of the bodies behind the challenge - said: "Viewers of the BBC drama, Bodyguard, may be shocked to know that the United Kingdom actually has the most extreme surveillance powers in a democracy. It can and must give us an effective, targeted system that protects our safety, data security and fundamental rights".
But the ruling wasn't all bad for British spies. "However, since the new Investigatory Powers Act arguably poses an ever greater threat to civil liberties, our work is far from over". The advocacy groups focused on the power granted by the Regulation of Investigatory Powers Act 2000 (RIPA), which was replaced in 2016 by the Investigatory Powers Act in 2016, a bill that hasn't yet gone into effect.
"This includes the introduction of a "double lock" which requires warrants for the use of these powers to be authorised by a Secretary of State and approved by a judge", the government said in a statement.
"We will push on with our High Court challenge against the Investigatory Powers Act and I'm sure we'll draw on the judgement of today to explain why it means that act is also unlawful", she added.More news: Ravens linebacker CJ Mosley carted off field with knee injury