The European Court of Justice struck a serious blow against the right of internet companies to hold unlimited information on individuals when it ordered Google to remove links that are deemed "inadequate, irrelevant or no longer relevant".
The court's decision will allow individuals the right to ask internet search engines to remove links to information about them that they do not want known - which could be seen either as an assertion of the right to privacy or an attack on free speech. Google and free speech activists reacted angrily to the court's verdict, which could guarantee individuals a "right to be forgotten" on the internet which is not currently available.
It is not clear just how the ruling will be implemented considering the sheer volume of online data and internet users. For individuals keen to erase embarrassing incidents from their past, it could prove a handy tool for reshaping their digital footprint, while data protection advocates are calling it a victory against the all-powerful internet giants.
But for champions of free speech, the potential for misuse is deeply worrying.
"This is akin to marching into a library and forcing it to pulp books," said Jodie Ginsberg, chief executive of Index on Censorship. "Although the ruling is intended for private individuals, it opens the door to anyone who wants to whitewash their personal history."
It was a repossessed home in Catalonia that sparked the battle between privacy campaigners, search engines such as Google and free speech advocates. Mario Costeja Gonzalez was dismayed to find searches on his name still threw up a 1998 newspaper article on past financial problems, even though many years had passed and his debts were paid off.
A Spanish court referred his request for the link to be removed to the Court of Justice of the European Union in Luxembourg, which ruled in favour of Costeja.
The judges decided search engines did have a duty to make sure data deemed "inadequate, irrelevant or no longer relevant" did not appear. Ordinary citizens could also request that search engines remove links to sites which contained excessive personal data on them.
Google had argued that it was not in control of the content - it was merely linking to it - and therefore the onus for removing any out-of-date information was on the websites themselves.
"We are very surprised that [this decision] differs so dramatically from the Advocate-General's opinion and the warnings and consequences that he spelled out. We now need to take time to analyse the implications," said a Google spokesman, Al Verney. He was referring to an opinion issued by an adviser to the European Court of Justice last year expressing concern that freedom of speech could be threatened.
This clash between the right to privacy and the right to information is an ongoing one in Europe. In 2012, the EU's executive arm, the European Commission, proposed a law granting people the right to be forgotten on the internet. The European Parliament watered it down, and internet companies have been lobbying member states not to approve the legislation.
They have an ally in the free speech groups, which argue that giving an individual the right to decide what can be removed from search engines with no legal oversight has worrying implications.
"The court's decision is a retrograde move that misunderstands the role and responsibility of search engines and the wider internet," said Ginsberg. "It should send chills down the spine of everyone in the European Union who believes in the crucial importance of free expression and freedom of information."
Costeja, the man who started it all, said: "It's a great relief to be shown that you were right when you have fought for your ideas, it's a joy."
Information and privacy
What does the ruling mean?
If, when you type your name into Google or any other big search engine, the results throw up information that is highly personal, sensitive or damaging, the relevant companies could be required to remove it.
Why is it a blow to freedom of speech campaigners?
Free speech advocates argue that the ruling creates a grey area about what information is deemed "inadequate, irrelevant or no longer relevant''. An individual with a shady past could exploit the proposed changes in legislation.
Who will it benefit?
Legal experts say the ruling, if made law, would benefit "Joe Public'' and not celebrities, sport stars and politicians where there is a genuine public interest. Internet companies, though, will have to decide for themselves whether someone is a public or private figure.