Google will implement a major upgrade of its AdWords product Monday, but many advertisers are unhappy about the forced changeover. Reuters

On Tuesday, the Court of Justice of the European Union ruled that Google must delete "inadequate, irrelevant or no longer relevant data" from its search results when requested to do so, a ruling which is expected to have important implications for the protection of people's data as well as significant implications for the tech companies throughout Europe.

UPDATE 2:53 p.m. EDT

The court’s ruling says that Internet search engines are responsible for how they process and reveal personal data appearing on web pages published by third parties. Google said it was “disappointed” in the ruling, as did competitors like Yahoo, Inc. (NASDAQ:YHOO). Yahoo says it is unsure of how the ruling will affect its business and users.

"Since our founding almost twenty years ago, we’ve supported an open and free internet; not one shaded by censorship,” a Yahoo spokesperson told the International Business Times. “We’re now carefully reviewing the European Court of Justice’s decision to assess the impact for our business and for our users.”

A representative from Microsoft, which operates the Bing search engine, declined to comment.

Why has the ruling been made?

The EU ruling was a test case against Google Spain which was brought by Spanish man Mario Costeja González who claimed that an auction notice about his repossessed house in Catalonia dating from 1998 should no longer appear when someone typed his name into Google.

González believed that as the case had been resolved the links to the auction (from the website of Spanish newspaper La Vanguardia) should be removed.

The court on Tuesday ordered La Vanguardia to remove the two links.

What has the EU Court ruled?

In their judgement, the judges said a search engine is "in certain circumstances, obliged to remove links to web pages that are published by third parties and contain information relating to a person from the list of results displayed following a search made on the basis of that person's name."

It means that while the original content will remain extant on the website in question, it will no longer be indexed by Google's search engine.

Does this mean a new legislation?

The judges ruled that the current EU data directive has already established a "right to be forgotten" which means the EU will avoid the long-winded process of having to address new data protection legislation.

When can I ask Google to remove links about me?

The ruling states that links to specific content may be removed when it is seen to be "inadequate, irrelevant or no longer relevant, or excessive in relation to the purposes for which they were processed and in the light of the time that has elapsed."

This means that information which was published lawfully and accurately at the time of an event (such as a bankruptcy ruling) could in time be removed from Google's results when someone searches for the person associated with the bankruptcy.

The ruling does not go into specifics about "time that has elapsed" and what it believes to be "inadequate or irrelevant" material, saying that this will be decided on a case-by-case basis.

Does it mean I can get rid of those embarrassing photos on Facebook?

Theoretically yes. Data protection lawyers believe this ruling will lead the way for links to photos or blog posts which show up on Google when someone types in your name, could soon be "forgotten". However it should be remembered that these photos and blog posts will still remain online on the original sites.

Will the ruling apply to other search engines?

Yes, once someone brings a case against Yahoo or Microsoft's Bing, then the same rules will apply.

What does it mean for those outside the EU?

The ruling is only applicable for Google search results within the EU. The reason is that Google had an operating base located in Spain, where the case was brought originally.

Questions remain about companies which don't have an operating base or sales operating in the EU - which is a lot of tech companies - and whether or not they will be forced to comply with the rules.

When you consider the Google servers which host the indexed search results which appear on a PC in Spain are likely to be located outside of the EU, it could allow Google to circumvent the court's ruling.

However, Viviane Reding, the European Commission's vice-president speaking after the result was announced claimed: "Companies can no longer hide behind their servers being based in California or anywhere else in the world."

The result could be a split on the internet.

For example, those searching for David Beckham in the US could see everything ever published about him online, while someone searching for Golden Balls in the UK could see a redacted list of links.

What content can be removed and when?

The ruling could create a lot of problems in relation to which content can be removed by Google and which will remain indexed by the search engine.

The ruling says "a fair balance" should be struck between the public's right to know and the "data subject's" right to privacy.

The problem is that we so far have no specifics about which content will be applicable and how long the courts believe is sufficient to allow particular content be indexed.

For example, will links to a celebrity's affair be left indexed for longer or shorter than your embarrassing photos of a drunken night out which appeared on Facebook? Will details about murder, rape or child pornography remain linked longer than a bitchy blog post you wrote about a former boss?

We will have to wait until the ruling begins to take effect and content is removed before we know how this will really pan out.

Is everyone happy with the ruling?

No. The Index on Censorship says this ruling "violates the fundamental principles of freedom of expression" and "is akin to marching into a library and forcing it to pulp books."

While this is an extreme reaction, there are some with more nuanced objections to the ruling. Big Brother Watch's Emma Carr told the Guardian:

"The principle that you have a right to be forgotten is a laudable one, but it was never intended to be a way for people to rewrite history. Search engines do not host information and trying to get them to censor legal content from their results is the wrong approach. Information should be tackled at source, which in this case is a Spanish newspaper, otherwise we start getting into very dangerous territory."

And Google is certainly not happy, despite its official response being couched in politically correct language:

"This is a disappointing ruling for search engines and online publishers in general. We are very surprised that it 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."

(Thomas Halleck contributed to this report)