Even in the most critical situations, when violence was the norm in relations between independent power centers, there were always playing predefined or otherwise agreed by the parties, accepted and respected as an adjunct power relations. Arguably, late historic times, the ground rules applied to these relationships did not possess legal characters, and they were based on religious concepts, or certain times in moral and philosophical approaches. In some cases not used certain weapons, possessing also the enemy. For example, packs of dogs were not used in fighting between Muslims and Christians. But these packs themselves were employed by the Spanish colonists in America against the Indians. If specifically targeting the documents and facts of history, is the existence of rules that govern relationships between independent power centers, which date back over 5000 years.The earliest agreement that is news is that held at the 3200 a. C. between the Babylonian cities of Lagash and Umma, in which both set their borders after a war. Another agreement would be signed between the Egyptians and the Hittites, by which they agree on the division of spheres of influence. In modern times, it seems that the first use of an international jurisdiction was that of the Alabama Claims, the end of the American Civil War, tried by an international court in Geneva. As regards the source of public international law, we affirm the existence of two positions: a / Some argue that this right has existed since primitive peoples maintained trade relations, forged alliances, put their problems to the decision of a third party, respected inviolability of his disciples, and so on.b / Those who deny the existence of international law in antiquity and locate its origin from the time they are given the basic assumptions for the existence of a system as it operates today: a plurality of nation states that are recognized as legally equal, attributed exclusively the attribute of sovereignty and are willing to regulate their relations by legal standards without undermining its character as a sovereign. These authors place the historical moment in which these events occur and international law appears from the sixteenth century, or more precisely, in the mid-seventeenth century, with the treaties of Westphalia of 1648.