Private law and private law relationships in Member States of the European Union are increasingly influenced by EU law. Sometimes, this influence is predictable, for instance because EU law provides expressly that violation of a rule shall produce a specific private law effect (Article 101(2) TFEU). Less predictable are the consequences where the Court of Justice interprets provisions of EU law ostensibly addressed to the Member States such as creating, modifying or extinguishing rights and obligations in legal relationships between individuals. Since 1974 the Court has given interpretations to such direct horizontal effect to some of the TFEU provisions on free movement.Private Law and the Internal Market seeks to establish the links between the relevant judgments and, by analysing them in the context of the various mechanisms used by EU law to influence national private law, considers whether the Court's approach to one free movement provision can be predictive of other free movement provisions and if so, to what extent.It also discusses the impact which accepting direct horizontal effect has on the grounds that must be available to individuals as a defence to alleged infringement of a free movement provision.