The theory of justice as fairness is a contractarian theory, which suggests the principles of justice that define the basic structure of a modern democratic society. The principles of justice in this theory focus the major social institutions, which assign fundamental rights and duties and shape the division of advantages that arises through social corporation. The basic structure, determined by these principles, aims to maintain background justice, which gradually tends to be eroded and undermined, because of historical, social, and natural contingencies. Thus continuous adjustments are necessary to avoid unjustified inequalities and restrictions on fair equality of opportunity.