The German Federal Supreme Court (BGH, decision of 26 November 2015, I ZR 3/14 and I ZR 174/14) recently acknowledged the general liability of TK-companies which provide access to the internet (so-called Access Provider) according to the principles of “Stoererhaftung” (Breach of Duty of Care) and thus closed a gap in current copyright law and practice.
The Access Provider might even be obliged to block certain websites (as ultima ratio), on which copyrighted works are illegally made available to the public, but only as far as the right holder has made reasonable efforts to take action against the party that initially committed the infringement (e.g. the content provider) or that has contributed to the infringement by providing services (e.g. the host provider). If claims against these parties fail or are devoid of any prospects of success and therefore a gap in legal protection would arise, taking measures against the Access Provider is reasonable. However, the rights holder has to make reasonable inquiries - e.g. by hiring a detective agency or a state law enforcement agency - to identify these parties.