Trade marks play a crucial role in our economy. By indicating trade origin, they facilitate the sale of trademarked products as well as signalling information about their quality. However, advancements in advertising enabled trade marks to become powerful tools that attract consumers and develop an aura that influences purchase decisions. While the main purpose of European trade mark law is the protection of the trade origin function, it also recognises and protects these âmodern functionsâ of trade marks, including the advertising, investment and communication functions. Tobacco plain packaging legislation is the latest development in tobacco control in the European Union and it also affects the functions of trade marks. It requires that the word marks of tobacco products should appear in a standardised way on tobacco packaging while preventing the use of any other trade marks. By doing so, tobacco plain packaging legislation aims to diminish the advertising, investment and communication functions of trade marks in order to reduce the power of attraction of trade marks and the influence they have on consumers. Tobacco plain packaging legislation is the first legislation that fully standardises the appearance of product packaging. This absolute nature of tobacco plain packaging legislation led to controversy and it was challenged, inter alia, under the provisions of the Agreement on Trade-Related Aspects of Intellectual Property Rights of the World Trade Organization and under the jurisdiction of the Court of Justice of the European Union. This thesis assesses the prohibitive provisions of tobacco plain packaging legislation in the light of the recently expanded rights given to trade mark proprietors under trade mark law. Through this assessment, it explains that the modern functions of trade marks recently recognised in the expansion of trade mark rights form the theoretical basis of the restrictive provisions of tobacco plain packaging legislation. Although they share the same theoretical basis, trade mark law provisions amplify the effect of the modern functions of trade marks while the provisions of tobacco plain packaging disable them. Therefore, this thesis uses tobacco plain packaging legislation as an analytical tool to examine the way trade mark law evolves. It evidences that the development of trade mark law is guided by the attribution of functions to trade marks and the balancing of the interests of the relevant parties involved. By viewing the development of trade mark law as the result of this two-stage process, this thesis argues that tobacco plain packaging should not be seen as an intrusive piece of legislation but as a legislation which is coherent with the development of the principles of European trade mark law. This thesis concludes that the way trade marks are used is shaped by the policy under which they are governed and as a result, trade mark law can play an important role in the enforcement of public policy considerations.