Despite its long history and influence, natural law theory has faced considerable criticism from various quarters.

Legal Positivism : The most significant challenge to natural law has come from legal positivism, particularly the works of H.L.A. Hart and Joseph Raz. Legal positivists argue that the validity of law is determined by its source, not its moral content. For them, a law is valid if it is enacted according to the proper procedures, regardless of whether it aligns with natural law principles.

Relativism : Some critics argue that natural law theories, with their claim to universal principles, fail to account for cultural and moral diversity. They suggest that what is considered moral or just varies greatly across different cultures, and a single, overarching moral code may not be applicable to all societies.

Empiricism and Scientism : Philosophers in the tradition of empiricism and scientific inquiry often reject natural law for its reliance on abstract concepts like "human nature" or "reason," which they view as unverifiable and unscientific. According to this view, law should be based on empirical evidence and observable social realities, not abstract moral theories.