How does the philosophy of law examine the relationship between law and morality?

The philosophy of law examines the relationship between law and morality by investigating whether legal validity depends on moral content. This inquiry has historically divided legal theorists into two primary schools of thought:1

• Natural Law: This tradition, championed by thinkers such as Cicero and St. Thomas Aquinas, argues that valid positive law is necessarily derived from objective moral principles. From this perspective, an unjust law fails to be a true law and lacks binding authority. In the 20th century, this framework was used to argue that the actions of the Nazi regime were not a central case of law due to their profound immorality.23

• Legal Positivism: In contrast, positivists seek to separate the question of what the law is from the question of what is morally right. By distinguishing between legal validity and moral goodness, positivists emphasize that not all laws are morally virtuous, which allows for the critical assessment of laws and the accountability of officials for actions that, while technically lawful, are morally reprehensible.3

Additionally, legal realism has challenged both views by suggesting that judicial decisions are often influenced by nonlegal factors, such as social norms or the personal ideologies of judges, rather than strictly by legal rules or moral principles.4