This treatise, current through October 2009, has been thoroughly revised. Chapter 10, Substantive Appraisal, explains the evolution in the Commission’s application of the substantive test. “As noted, Advocate General Kokott endorsed a 'balance of probabilities' test, opining that the Commission should not be limited to prohibiting concentrations only where it was 'very probable' or 'particularly likely' that such operations would have an adverse competitive effect. Where the Commission approves a concentration, opinion is divided between those who contend that the standard of proof is lower than in the case of a prohibition decision.” The author begins by stating that “Merger control is a predictive exercise ... there will rarely be direct evidence of the competitive effect of that concentration ... The need for clear, robust, and persuasive evidence is therefore at the heart of effective merger control. The Merger Regulation is silent on the evidentiary principles that apply in merger control proceedings, notably with regard to the burden and standard of proof.” The completely revised section of this chapters explores in depth these standards and burdens of proof.