In the first part of the thesis it is argued that international justice is, indeed, possible even in a world in which there is no central authority vested with the power to enforce the principles that inform it. Two arguments put forward by the theory of political realism that are designed to demonstrate that the application of moral principles and the principles of justice is confined to the territory inside a state are considered. The first realistic argument claims that international relations, by analogy with Hobbes's state of nature at the individual level, are governed by anarchy which makes it irrational for states to observe the principles of justice since there are no guarantees that they will be observed by other states. However, this analogy is unsustainable due to the differences that exist between agents on the international and individual levels. Compared to the insecurity of the state of nature, the level of insecurity of international relations is lower, which makes it possible for co-operation between states to be established. This is additionally corroborated by some findings of the game theories. The paper goes on to refute second justification laid down in support of the second realistic argument that builds on the proposition that national interest is the supreme value upon which states rely in their behaviour on the international level. The central part of the thesis is dedicated to the contractualist approach to the normative foundation of international justice. By combining some insights ensuing from Rawls's Law of People with Scanlon's approach to the foundation of ethics it attempts to show that the contents of the principle of justice is determined by a group of principles that no agent participating in international relations could reasonably refute as the basis for an 210 informed, uncoerced, general agreement. In an ideal theory parties to an agreement involve state representatives that within the framework of non-ideal theory are joined by representatives of other agents of international relations, i.e. intergovernmental and nongovernmental organisations and multinational corporations. In both cases the parties will agree on the principles of justice based on respect for basic human rights. Special attention is paid to democratic rights that play a double role: at the state level they guarantee that other rights will be observed, while at the international level they safeguard the stability of the international order based on the idea of the democratic peace. The closing part of the thesis uses the example of international distributive justice to present the arguments designed to show that the obligations ensuing from the principle of international justice do not necessarily correspond to the obligations ensuing from the principle of justice as it applies to domestic society. In contrast to the proponents of the thesis that the egalitarian principles of distributive justice that apply to domestic society also apply at the global level, the paper argues in favour of Rawls's proposition that the agents involved in international relations would agree on a less demanding principle that embodies the duty of assistance. This principle is aimed at establishing a just social and political order within each society that forms part of the international community.