Having recognized this darker side of human nature within ourselves mankind has retaliated by establishing bodies of law to act as barriers between us and destruction. Although these barriers cannot ultimately stop us in our quest for more, they do serve as a guide to morality. In a statement made by Kofi anan, the charter of international law is described as that of "policing international crimes and punishing those who commit them".
Over the course of the last century the cause of policing and punishing those who commit international crimes has been furthered by numerous bodies of legislation. The first of these to gain international recognition for the humanitarian cause as well as that of a country's sovereign independence was the Geneva Conventions of 1949. These conventions were sparked by atrocities such as the holocaust and of the treatment of prisoners of war during W.W.2. The establishment of the Geneva Conventions has led the way in establishing international legislation in relation to warfare both directly and indirectly.
Such examples of legislation have manifested themselves in the Chemical weapons convention of 1993, the establishment of ICITY, the Nuremburg principle, as well as the UN. Since the implementation of these bodies world leaders have been forced to rationalize their nation's national interest against the consequences. As these consequences usually imply personal responsibility, especially in regard to crimes against humanity, hope is created through realizing that, like you and me, leaders are not above the consequences of the law.
With this personal or "command responsibility" being taken into account, international law has progressed to punishment on an individual basis as oppose of economic exemptions that punish the whole country. This is much akin to a country's national law where by a person illegally appropriating your property is also punished for their actions.