The Federal Constitution gives the public advocacy status of Essential Function to justice. The activity is regulated in arts. 131 and 132 of the Federal Constitution. At the federal level, public advocacy is played by the General Advocacy of the Union, composed by careers of the Attorney of the Union, Prosecutor of the National Treasury, Prosecutor Federal and Prosecutor of the Central Bank. The art. 131 of the Federal Constitution states that "the General Advocacy of the Union is the institution which, either directly or through a subordinated agency, represents the Union judicially and extrajudicially, and shall, in accordance with the complementary law which provides for its organization and operation, consulting activities and legal advise of the Executive." In democracy the role of the State should be directed to meet the interests and needs of society, always seeking to promote the common good and the integral development of the human personality. Considering that all power emanates from the people, as provided in art. 1, par. one of the Federal Constitution, are the social needs that will define the course role of the State. The role of the Public Attorney should always be grounded in the thin thread between the need to provide legal mechanisms to meet the collective needs at the same time it plays an important preventive role for fundamental rights and guarantees of citizens do not violated by State agencies. The study to be developed comes from the premise that the State should hold authority without becoming authoritarian; must ensure the collective interests without destroying individual ones; the State should be the unifying element of all the interests of their people without adopting contradictory positions or act contrary to the fundamental goals of the Constitution of the Federative Republic of Brazil; It should aim at building a fair society without acting unfairly. The Essential Functions to Justice, particularly those held and organized by the State, must be imbued with that purpose. With public advocacy is no different. The public advocacy need detain autonomy and sufficient independence to contribute more effectively to the social peace through preventive actions to combat deviant behavior and internalization of propositional attitudes in order to reduce litigiousness. The independence of the public attorney is essential for behavioral change in a tough State, turning it into a conciliator, compromising State, by the spontaneous recognition of its mistakes for proven citizens rights recognition purposes. Thus, we seek with this paper to precisely analyze the primary purpose for which it was constitutionally created the General Advocacy of the Union, discuss the autonomy and independence of the federal public attorney, his/her extent and limits, his/her enabler role of public policies and the need to act with the utmost good faith regarding for the rights and guarantees of citizens.