This thesis discusses the access to and the exercise of contestation in the Dispute Settlement Body (DSB) of the World Trade Organization (WTO). The general objective of this study is: i) to investigate the extent to which the level of development of countries, marked by power, commercial performance, legal capacity, and technical capacities, influences the time, the continuity and the regularity of the access to contestation in the DSB; and ii) to analyze how two countries from the Global South, Bangladesh and Brazil, exercise the contestation of the multilateral trade system norms through the DSB of the WTO. The theoretical framework of this thesis is grounded on Antjie Wiener s theory of contestation (2008, 2014, 2017, 2018), which assumes that the relations between the actors and the norms that govern the international system is cyclical, based on what she calls meaning-in-use. The term indicates that the (re-)signification of norms is the result of the interactions among actors (governed agents). In this regard, norms are (re)created based on the various ways in which their meanings are interpreted, which occur through the actions, discourses, decisions, strategies, among others, of the governed agents. This relation between governed agents and norms is referred to as contestation by the author. In this thesis, contestation was observed using two methodological approaches: quantitative (chapter 1) and qualitative (chapters 2 and 3). Chapter 1 presents three types of analyses: descriptive statistical, nonparametric, and econometric. The flagship was Survival Analysis, which is a methodological tool with a double dependent variable: time-event. The empirical analysis found that variables of power (GDP, population, continent, and development status), legal capacity (member of the ACWL), and technical capacity (number of articles published) were significant for the events of initiating, responding to, winning, or losing a dispute. The data also showed that quantitative variables have a greater influence on the access to contestation (opening and responding) than on the exercise to contestation and the contestation process itself (winning and losing). The variables specific to the disputes (subject matter, number of agreements challenged, phases, among others) were not statistically significant for any of the events. The quantitative analysis led to the identification of two deviant cases, that is, two countries whose contestation was not as expected: Bangladesh and Brazil. Chapter 2, therefore, provides a case study of Bangladesh s exercise of contestation in the institution. From the documentary analysis and the literature review, it was verified that the Bangladeshi contestation on the dispute over the anti-dumping measures applied by India in relation to Bangladeshi exports of lead-acid batteries (DS306) emerged as the result of pressure from the company Rahimafrooz, the media, and internal and external institutions. Chapter 3 focused on Brazil’s exercise of contestation in the institution, based on interviews, documentary analyses, and literature review. The empirical material showed a significant role of the Brazilian diplomatic corps in a constant and efficient exercise of contestation. Furthermore, there were indications of different forms of contestation among those working in Brasília when compared to those working in Geneva. Gender issues were deemed tangential to the Brazilian exercise of contestation, especially based on the low number of female representatives and their relations with other delegations. The study also revealed a considerable involvement of law firms and a cross-cutting impact of the epistemic community in the exercise of contestation. Finally, as concluding remarks, the benefits and pitfalls of conducting quantitative research in the field of International Relations in Brazil were highlighted, and some of the indirect contributions of this thesis to the academic community, to the actors who participate in this type of contestation, and to society in general were raised.