Among efforts of community cooperation worldwide, the Andean Community in South America is a notable example. This sub-regional organisation aims to achieve social and economic cooperation among its Member Countries with a view to the gradual formation of a Latin American common market. To attain this objective, the Cartagena Agreement provides, among other measures, the possibility to implement a trade Liberalization Program, aimed at eliminating any restriction or levy that affects imports of products originating in the territory of any Member Country. This paper focuses on the analysis of that Program, and how it falls within the so-called ‘constitutional’ or ‘original’ sources of the Andean legal system. It also examines the attributions of the Andean Community General Secretariat to determine through an investigation procedure whether a particular measure constitutes a levy or restriction.