This study provides a fresh understanding of the theory of trademark law, more specifically the functions of trademark through the legal historical analysis of trademark law in the colonial and socialist era of Vietnam from 1858 to 1986. It argues that unlike widely accepted agreements 1 | ON THE FUNCTIONS OF TRADEMARKS FROM WESTERN LEGAL VIEWPOINTS Conventional wisdom has it that trademark functions primarily to "identify the origin or ownership of the goods to which it is affixed" (Schechter, 1927; Strasser, 2016). It is said that trademark is used to support consumers' understanding and perception that if two or more similar products bear the same trademark, they should come from the same source, although the consumers might not know the identity of the source (Naser, 2008; Schechter, 1927). Since its juridical endorsement by the Supreme Court of the United States in its famous case of Hanover Star Milling Co. v. Metcalf of 1916, this orthodoxy definition has been translated into worldwide statutory and regulatory provisions (Bently, 2008). The Lanham Act defines trademark as "any word, name, symbol, or device, or any combination thereof" "to identify and distinguish his or her goods, including a unique product, from those manufactured or sold by others and to indicate the source of the goods, even if that source is unknown" (Lanham Act, 15 U.S. Code Chapter 22-Trademarks, n.d., sec. Section 45 15 U.S.C. § 1127). Directive (EU) 2015/2436 of the European Parliament and of the Council of 16 December 2015 relating to trademark also uses a similar language when stipulating that: A trademark may consist of any signs, in particular words, including personal names, or designs, letters, numerals, colours, the shape of goods or of the packaging of goods, or sounds, provided that such signs are capable of: (a) distinguishing the goods or services of one undertaking from those of other undertakings (Directive (EU) 2015/ 2436 of the European Parliament and of the Council of 16 December 2015 to Approximate the Laws of the Member States Relating to Trademarks, 2015, Section 3); The 2005 Intellectual Property Law of Vietnam as amended subsequently defines a trademark including service marks as a sign to distinguish (similar) goods, services of different individuals, organisations. The law then goes on to further specify that the sign shall be visual. That is to say it excludes sound trademark or scent trademark from its