A German court has ruled that a shopping site's use of the Facebook 'Like' button was not legal, since users were not properly warned that their personal data was being shared with the social network.
The Düsseldorf district court said that the Fashion ID clothing website, run by retailer Peek & Cloppenburg (P&C), failed to get the right approval from users before transferring some of their browsing data to Facebook.
The case was brought by the North Rhine-Westphalia Consumer Association, who claimed the site transferred data to Facebook through the 'Like' button, regardless of whether they even used it or not.
The court said that the practice violated Germany's tough data protection laws, and the retailer could have to pay a penalty of up to €250,000 (£192,000), according to Reuters.
Now, P&C and other retailers will have to explicitly warn users that liking their pages on Facebook from their sites will allow the social network to log some of their data.
The consumer group has also issued warnings to five other websites which it alleges have similar practices.
The case came just after a January ruling which said Facebook's 'friend finder' feature, which lets users encourage their email contacts to sign up for the site, constituted a deceptive marketing practice.
Germany's competition regulator also announced last week that it had opened an investigation into suspicions that Facebook is using its leading market position to impose unfair conditions on its users.
P&C will be able to appeal the ruling, but it told Reuters it will wait for the court's written judgement before deciding.
They also said it had changed how the site uses the 'Like' button, by getting users to consent before sending any information to Facebook.
A spokesman for Facebook said: "This case is specific to a particular website and the way they have sought consent from their users in the past."
"The 'Like' button, like many other features that are used to enhance websites, is an accepted, legal and important part of the Internet, and this ruling does not change that."
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