This chapter will determine and evaluate the role of the general principle prohibiting the abuse of rights in the enforcement of human rights in contractual relations, essentially from the angle of Belgian law. Whereas this principle has been created and developed in private law relations, the influence of international human rights has increased the importance of the discussed principle. It will be demonstrated on the basis of the Belgian case law that the criteria to find an abuse of rights constitute appropriate tools to enforce human rights in contractual relations (e.g., the right to non-discrimination, the right to human dignity or the right to privacy). As such, these criteria and the technique of judicial review, which are applied in private law relations, have been concretised or modulated in light of the proportionality test used in the protection of human rights in vertical relations.