Begun in the 19th century, Labour Law underwent numerous modifications until it was consolidated. Before it became a branch of the Law itself, labor relations were constantly changing, to the extent that there were sometimes no rules to regulate them; sometimes the regulation was excessive, hindering the exercise of the autonomy of the will and, consequently, the maintenance of numerous jobs, since many employers were unable to bear the burdens attributed to them by the severe labor laws.In order to mitigate the imperativity and rigidity of the current constitutional and legal rules dealing with labor rights, there was the emergence of the institute called flexibilization, which aims to preserve workers' rights but allows for the elasticity of the rules governing employment contracts, in order to benefit employers as well, relieving them of some burdens that almost always put the maintenance of jobs at risk.