Based on a thorough review of the legal framework and interviews, this study analyzes the way in which public secondary school principals in the Federal District deal with cases of underperforming teachers. Poor performance is not limited to technical-pedagogical failures, but includes lateness and absences, as well as mistreatment, harassment or sexual abuse against students. It concludes that the main obstacles faced by educational authorities in applying the corresponding sanctions are the lack of training (legal and administrative) of the principal, inadequate laws that overprotect teachers who hold a permanent position, and the lack of a legal standard to evaluate technical-pedagogical performance and union representatives. Finally, several recommendations are made that could be implemented to improve the current situation.