aequitas

Aequitas is a Latin term meaning fairness, equity, or justice. It derives from aequus, meaning level or even, and in classical usage often referred to a measured, reasonable approach to judgment and action. The word embodies the idea that legal and social rules should be applied with regard to the balance between strict letter and universal sense of right.

Historically, aequitas played a central role in Roman jurisprudence as a corrective principle to avoid unjust outcomes produced by rigid application of the law. It was later developed in medieval and Scholastic thought as the idea of equity—an informal supplement to ius (law) that guides interpretation and application in light of reason and the common good. Philosophers such as Thomas Aquinas described equity as a virtue that perfects law by adapting general rules to particular circumstances, preserving justice when literal rules would fail.

In modern usage, equity remains the closest English equivalent to aequitas. Many legal systems distinguish between the strict remedies of law and the more flexible relief of equity, allowing judges to temper rules to achieve fair results. Beyond law, aequitas informs moral and political discourse on distributive justice, contractual fairness, and the alignment of rules with ethical considerations.

Today, aequitas is principally a historical and philosophical concept used to discuss fairness and the appropriate balancing of duties, rights, and consequences. It appears in discussions of canon law, philosophy of law, and moral theology as a term for the virtue of applying universal principles to concrete situations.