Due process of law is a guarantee of the citizen, that it of the constituent a, assuring in such a way the right of action of access to the Judiciary Power, as the procedural development in accordance with norms previously established. As doctrinal concept on this I begin, I cite what it are said for Cintra in its book of the General Theory of the Process: ' ' due process of law, as constitutional principle, means the set of guarantees of constitutional order, that of a side assure to the parts the exercise of its facultieses and powers of procedural nature e, of another one, legitimize the proper jurisdictional function. One notices that most important of the principles it is of due process of law, since assuring this, one will be guaranteeing the too much principles elencados in Federal' constitution; '. In short, the Constitution displays that he is assured to the individual the right of being processed in the terms of the law, having guaranteed still the contradictory, legal defense and a impartial judgment. I begin of the Isonomy This relating I begin this displayed in the article 5 Caption of the Constitution with the following definition: Art. 5 – All are equal before the law, without distinction of any nature, guaranteeing themselves it the Brazilians and to the resident foreigners in the Country the inviolability of its right to the life, the freedom, the equality, the security and the property, in the following terms: For Nelson Nery Jnior ' ' to give isonmico treatment to the parts means to differently treat equally equal and the different ones, in the measure of its desigualdades' ' He is not only in the caption of the article 5 that we can see the beginning of the isonomy, we can cite as the example, the inversion of responsibility of the test you deal in them that they exist between consumer and the supplier.