The European Union's top court says website owners could face legal risk over Facebook's ubiquitous "Like" buttons. The Court of Justice of the European Union ruled today that site owners could be held liable for transmitting data to Facebook without users' consent -- which appears to be exactly what happens when users visit a site with a Like button, whether or not they click it.

The ruling doesn't stop Facebook, or other companies with similar widgets, from offering these options. But sites must obtain consent from users before sending data to Facebook, unless they can demonstrate a "legitimate interest" in doing otherwise. Right now, data gets seemingly sent to Facebook as the page loads -- before users have a chance to opt out. So in the future, sites might have to approach Like buttons differently.

Such as the Facebook button just at the top of this page...