One of the modern lines of the Russian competition law is strengthening of public sanctions for its infringement. However practical application of these sanctions is possible only at full conformity of circumstances of concrete case to all conditions of application of measures of responsibility. These conditions are listed in the administrative legislation, in the criminal code and in the Law on protection of a competition of 2006. Russian and foreign legal practice shows that the most difficult for the determination are boundaries of the product market where there was an anticompetitive offence. What are the practice of application and prospect of updating of rules of a proof of such boundaries? The present article also is devoted the analysis of this point in question. The author shows features and lacks of use of economic arguments at interpretation of legal concept «the product market».