No law may establish provisions that alter the intangibility and escalation of rights and labor benefits. In labour relations prevailing reality on forms or appearances. Article 93 (CNRBV): The law will guarantee stability in the work and have it conducive to limit all forms of dismissal not justified. ratified by the provisions reflected in the to Art. 60 lit. (e) the lot in accordance with Art. 8 lit.

(c) and (d) of its rules of procedure. Article 60 (LOT): In addition to the constitutional and legal provisions of imperative character, for the resolution of a particular case will apply, in the order indicated: e) principles universally accepted by the labour law; Article 8 (Rgl.LOT): the principles referred to in subparagraph e) of article 60 of the organic labour law are, among others, and without prejudice to its express forecast in labour legislation, as follows: c) primacy of reality or the facts, face the shape or appearance of acts arising from the legal relationship – labor. ((d) conservation of the employment relationship: i) presumption of continuity of the employment relationship, by virtue of which, in case of doubt about the extinction or not this, shall be settled in favour of their subsistence. (ii) preference of the labor contracts for an indefinite, in attention to which exceptional must be allocated to the assumptions of authorization term contracts provided for in article 77 of the organic labour law. And limitations established by law to the use of employment contracts to certain time: article 77 (LOT): the employment contract may be concluded for a time determined solely in the following cases: to) where required by the nature of the service. (b) is intended to replace interim and lawfully to a worker; and (c) in the case provided for in article 78 of this law. We can conclude the existence of a presumption of law which assumes that the contract of employment by their nature and purpose, is a relationship legal agreed indefinitely; and is it supported only by way of exception, in time determined, when occurs any of the circumstances provided for in Art 77 of the LOT.