This research article analyses the principles of supremacy and direct effectiveness of community law. Within this purpose, a brief conceptualization of each principle under the European and Andean community law is pointed out highlighting their main characteristics as well as judicial decisions that supported them. Later on, the research focuses on a brief analysis of the Comcel vs. ETB (Colombia) case through which the application of the principles that make part of the theoretical support of this research can be observed. Lastly, the relevant conclusions of the research are presented.