To define international law:
1. International law consists of rules and principles governing the conduct of states and international organizations in their interactions.
2. It is binding on civilized states in their relations, as recognized under treaties and customary practices (e.g., UN Charter).
3. It is not limited to customs or legislations alone, nor solely about domestic justice administration.
Therefore, the correct answer is (2) Body of rules and principles of action which are binding upon civilized States in their relation with each other.