The aim of this work is to identify and analyze the legal problems arising from applying the articles of the EC Treaty on the prohibition of quantitative restrictions and measures having equivalent effect. The author, referring to evolution of the case law of European Court of Justice, reveals problem aspects of the prohibition of quantitative restrictions on import and measures having equivalent effect, ensuring the free movement of goods in EC. The author analyzes the link between the list of mandatory requirements, introduced in Cassis, and the article 30 of the Treaty, looking for bonds between them and providing possible solutions of the problem. The author also presents the probable reasons of the large-scale criticism towards European Court of Justice due to its ambivalent decision in Keck, examines the arguments rehabilitating Keck and estimates the influence of Keck towards free movement of goods in EC. The author aims to reveal the tendencies of European Court of Justice in the context of market access and discrimination, comparing both tests and considering whether it is possible to apply one of them alternatively or use a synergy of both tests. The basics of this work are focused on legal doctrine given in monographs, articles and publications of various foreign legal authors.