In the current system of EC antitrust enforcement, the European Commission combines the investigative and prosecutorial function with the adjudicative or decision-making function. The purpose of this article is to analyse the advantages and disadvantages of this system, in comparison with a system in which the adjudicative function is separated from the investigative and prosecutorial function, such as the US system in which the Department of Justice or the Federal Trade Commission (under the pre-merger notification programme) investigates and prosecutes before a federal court. The first chapter of the article contains a description of the current EC system, a comparative description of the US system, an overview of the legal debate on the compatibility of the current EC system with Article 6 ECHR and on the scope for change under the current EC Treaty, and an introduction to the wider policy debate. The second chapter deals with accuracy, in particular the question whether there is a risk of prosecutorial bias in a system in which the investigative and prosecutorial function is combined with the adjudicative function. The third chapter deals with administrative cost, in particular the question whether a system in which the European Commission would prosecute before the Community Courts would be more expensive or slower than the current system. The fourth and last chapter contains a summary and conclusion.