As part of an investigation into a possible cartel, the Commission had visited the companies in 2009, and in 2011 asked them to answer a questionnaire on suspected infringements.
In 2014, several companies including German HeidelbergCement and Schwenk Cement and Italian Buzzi Unicem and Italmobiliare asked the EU General Court for this demand to be annulled, saying that the Commission was asking for too much information and in a 'burdensome format'. The General Court refused and upheld the Commission's position.
The Court of Justice of the European Union (CJEU), Europe's highest court, has now set aside both the Commission's decision and the General Court's judgement. The General Court was wrong to find the Commission's decisions 'adequately reasoned', it said.
Questions sent to the companies were "extremely numerous and cover very different types of information", and it was not possible to tell whether the information was needed for the investigation, the CJEU said.
When requesting information the Commission should set out the legal basis and purpose of the request, specify what information is required and fix a time-limit for it to be provided.
This is important in order to show that the request for information is justified but also to enable companies to judge the scope of their duty to cooperate and their rights of defence, the CJEU said.