Collective Negotiation is a practice and an institution of normative status. It is the former because the Collective Agreement, in any of its variants, regulates the working conditions of the majority of employees: the working day and its distribution, professional classification and promotion, and the regulation of occupational health and safety. It is the latter, because, even following constitutional requirements and regulations of other levels, the autonomy of the agents authorized under current legislation is so broad that it can determine the negotiable areas, the duration of agreements, the negotiation structure and its contents.