Why did Jeremy Bentham criticize English common law?

Jeremy Bentham’s critique of English common law was rooted in his belief that the system was theoretically confused, practically dangerous, and fundamentally incapable of serving as law in the fullest sense. His objections focused on several key areas:1

• Conflation of Law and Morality: Bentham criticized theorists like William Blackstone for failing to distinguish between what the law is and what it ought to be. He argued that this confusion stifled necessary legal reforms required to address the changing social and economic conditions of the 18th century.1
• Lack of Accessibility: He viewed the common law as an exclusive domain of a professional elite—judges and lawyers—who used obscure, technical language to maintain a "myth" of expertise. Bentham believed that for law to effectively guide behavior, it must be accessible and understandable to ordinary citizens.1
• "Dog Law": Bentham mockingly labeled common law as "dog law" because it developed on a case-by-case basis through retrospective application. He argued that because judges did not clearly declare rules in advance, citizens were punished for breaches without having been given rational guidance on how to avoid such liability in the future.1

Ultimately, Bentham advocated for the codification of law, defining it as a clear command from a sovereign that could provide the certainty and utility necessary for the "greatest happiness of the greatest number".12