The reason for the EC's concern is that ContentGuard owns key patents based on early 1990s work by Mark Stefik, a researcher at Xerox's Palo Alto Research Center, on DRM technologies. These include machine-readable markup languages to attach rights to content so that, for example, an article could be read but not printed, or a rights-holder could specify how many times a song could be played. The technologies also include the ability to attach fee-charging mechanisms, and other such basic DRM ideas.
Good job too since American regulators have rubber-stamped it. It is cases like this which clearly show why Europe should become more united so that there is at least one body able to scrutinise monopolistic behaviour by arrogant conglomerates