The effect of the employment legislation is to govern the use of the employer's power rather than to grant him such a power. Under this legislation, the different unilateral actions of the employer are subjected to distinct legal systems: dismissal, disciplinary actions, modification of work conditions etc. However, individual employment agreements as well as collective labor agreements can be sources of authorization of the employer's power. In such case, the employer's power demonstrates an original character: it must be operated not only within the conditions defined by the employment legislation, but also in the limits of the contractual obligations agreed with employees.