According to Polygon, the VZVB, aka the Federation of German Consumer Organizations, are planning to take Steam to court before the end of the year over the digital distributors refusal to change their policy on used games. Currently, any games purchased from the service cannot be resold, which Eva Hoffschulte, a VZVB representative, says violates European Law.
In February of this year, the European Court of Justice ruled that consumers have to right to re-sell digital goods. Following this decision, the VZVB sent Valve a cease-and-desist letter as the companies terms and conditions were in conflict with this law. With still no change to Steam policy, a day in court in the next step.
If the lawsuit is successful, it would mean that users could sell their unwanted games freely in the Steam market. How this would impact the service overall would be a different story.