This chapter explores the concept of ‘art’ from the perspective of law, art history and aesthetics. Drawing on examples from the visual arts, it discusses the concept of ‘art’ in light of Plato’s philosophical ideas, Weitz’s argument about art as an ‘open concept’, Danto’s philosophical investigations and the ‘institutional theory’ of the art. It further draws upon various areas of international law, including cultural heritage law and intellectual property law, in order to demonstrate that a precise definition of ‘art’ is not offered at present in any international instrument. The chapter further examines the legal challenges arising from the ‘non-definition’ of the concept of ‘art’, questioning the validity of the argument of artistic freedom as an exception to rules of general application. Last, the chapter details the need for legal protection against abuses and potential dismissal of artworks as ‘non-art’, in instances where the qualification ‘art’ (and consequently the question of artistic merit) plays the role of a ‘defence’ against attempts to interfere with freedom of speech.