The latest Revision of the Environmental Remedies Act (ERA) not only extended the possibility of collective legal action, but also caused different modifications in the German “error of law-doctrine”. Because of the opaque way of regulation, various of these profound amendments aren’t recognizable at first. Therefore a systematization of the regulatory arrangement is needed. The article provides an analysis of the regulatory framework of the ERA, especially focusing on the Law to challenge the substantive and procedural legality of decisions, acts or omissions and the legal concept of class action in the ERA.