Section B of Article 123 of the Mexican Constitution covers the workers of the federal Powers of the Union. Fraction VII states: “La designación del personal se hará mediante sistemas que permitan apreciar los conocimientos y aptitudes de los aspirantes” (Staff shall be appointed through systems that allow the knowledge and aptitudes of the applicants to be assessed).
Fraction VIII gives them rights to a promotion ladder, the escalafón, “a fin de que los ascensos se otorguen en función de los conocimientos, aptitudes y antigüedad” (so that promotions are granted on the basis of knowledge, aptitude and seniority).