With the current crisis of legitimacy of political power, relevant questions have arisen about ethics in politics and, consequently, the effectiveness of party loyalty. The excessive number of migrations between parties, not infrequently without the presence of just cause provided for in TSE Resolution 22.610/2007, implies the subversion of the popular will demonstrated at the ballot box. The constitutional principle of party loyalty acts to protect the sovereignty of the people, above all so that the public interest of participatory democracy prevails over the private interests of political office holders.