Where is no plaintiff, there is also no judge: Private enforcement of competition law presupposes that there are plaintiffs who take a cartel to court. Plaintiffs exist where actions are worth it. Cartel victims may obtain compensation of many millions or even billions. In general, however, the hurdles in the German Code of Civil Procedure (ZPO) are high as the plaintiff must demonstrate and prove all the facts substantiating the claim. If the legislator wants to have as many plaintiffs as possible he must therefore reduce the burden of proof. Already under the rules previously applied there were some alleviations of the burden of proof. With the 9th amendment of the German Act against Restraints of Competition (GWB) the legislator has removed another hurdle. The following article provides an overview of what is certain, what is presumed and what can be estimated in cartel damage litigation after the 9th amendment of the GWB – and therefore does not need to be proven (any more).