This research will look at the practice of trade union activity in Brazil, from the perspective of trade union plurality, which goes against the provisions of the 1988 Federal Constitution, i.e. the provision for a system of trade union unity. However, this is in line with the International Human Rights Treaties that Brazil has ratified, which guarantee all workers the right to exercise the right to free association, including for labour purposes, the most legitimate exercise of trade union freedom. When referring to the defence of these rights, there is a direct relationship with Democracy and Freedom; moreover, without freedom one cannot speak of Democracy and vive-versa. The research seeks to present a critique of the Brazilian regulatory system, whose structural basis is trade union uniqueness, through a conceptual and historical analysis from the perspective of the principle of trade union freedom.