正義原則所要求的是：社會關係應符合公平。由正義原則可以演譯出兩個原則：應有待遇原則及相同待遇原則。正義原則是一個形式原則。正義原則的適用，是指針對特定的社會關係具體化正義原則，經由此種方法可以產生得適用於社會關係的具體原則。法律學者經常以特定的術語來表述由正義原則具體化出來的原則，如：保護正義、修正正義等。亞里斯多德提出兩種社會關係的基本模式：上下關係及平行關係。將正義原則適用於上下關係而生的原則，謂之「分配正義」。將正義原則適用於平行關係而生的原則，謂之「平衡正義」。正義原則是自然法原則之一。因此，正義原則的適用應配合其它自然法的原則為之。法是形成社會關係的重要工具之一，因此，法律的內涵及其適用應符合正義原則。

The principle of justice demands fairness in social relationship. Two principles are inferred from the principle of justice, that is the principle of suum cuique tribuere and the principle of equality. The principle of justice is a formal principle. To apply the principle of justice means to concretize the principle of justice in view of a given social relationship. By this way we can obtain the concrete principles, which can be applied to the given social relationship. Legal scholars tend to use special terms to donate the principles which are applied to the given social relationship, such as, Justitia protectiva, Justitia correctiva. Aristotles is the first person who advocates that there are two basic patterns of social relationships: the superior and subordinate relationship and the parallel relationship. The principles inferred from the principle of justice in view of the superior and subordinate relationship are called Justitia distributiva. The principles inferred from the principle of justice in view of the parallel relationship are called Justitia commutativa. The principle of justice is one of the principles of natural law. The application of the principle of justice should be in harmony with other principles of natural law. Law is the fundamental tool to shape social relationship. The content of law and its application should accord with the principle of justice.