The Court of Justice of the European Union (ECJ) ruled that online retailers must warn web users that they send personal data to Facebook when they click on the 'like' button embedded on the retailer's site. According to the decision, users should be asked to consent to their data being gathered. The case was brought by Verbraucherzentrale NRW, a German consumer protection group, against online clothes site Fashion ID, which embeds a Facebook button. Under EU data protection law, the Fashion ID and Facebook are jointly responsible for gathering the data. Bitkom, a German trade federation for online businesses, criticised the ruling, lamenting the burden placed on website operators. They warned that the decision would go beyond Facebook and potentially effects all social media plug-ins, which are important for firms to expand their reach on the web.