H. L. A. Hart’s concept of legal positivism was heavily influenced by Austin. However, he breaks with Austinian positivism at three vital junctures. First, he believed that the sovereign law giver is defined by his office rather than being a person who has secured the habit of obedience. Second authority is vested in rule of recognition instead of through the threat sanctions. Finally, Hart believed that laws expand liberty rather than limit it. In a nutshell Hart’s Philosophy of Law builds upon the Command Law Theory established by Austin, corrects its errors and establishes its own doctrines.

In his essay “Sovereign and Subject”, Hart proposed that the habit of obedience does not account for the relationship between subject and sovereign. This inclination to, or habit of obedience, propounded by Austin, asserts that there exists a relationship between a subject and his sovereign. Where this relationship exists we speak of a society. However, since the habit of obedience is a habit backed by threats, it differs little from the idea a gunman coercing a person to give him his purse.

Hart opines that a law’s validity does not depend on the existence of social rules. Instead laws exist to promote social order. Hart contributes his conceptual analysis theory to jurisprudence of legal formalism. He postulates that jurisprudence aims to give analysis of the uses to which the concept of law is put in various social practices. Given that all rules have a penumbra of uncertainty, a judge must often choose between alternatives. Simply put, Hart takes legal thought beyond the simplistic Command Theory.

To him a law can be valid despite its moral invalidity and sans any coercion backed by threats. Such views on the law can be seen today in the USA Patriot Act. This is morally reprehensible because of the many provisions that potentially violate citizens’ rights. However it is still a valid law promoting the security of American society at large. As a legal naturalist Ronald Dworkin rejects positivism. His chief objection is that moral principles can be binding by virtue of the fact that they express an appropriate dimension of justice and fairness.

He espouses the belief that in interpreting the meaning of valid legal rules, it is often necessary to consult moral principles. Curiously, a posthumous edition of Hart’s seminal A Concept of Law gives space to Hart’s response to Dworkin’s criticism of Legal Positivism. In contrast to Hart, Dworkin believes that law is not simply a matter of rules. Moral principles are law even if they are not identified under the rule of recognition. Moral principles can also be said to be law because they have dimensions of justice.

As opposed to Hart, Dworkin’s theory on jurisprudence is that judges appeal to binding legal standards that are more discretionary than hard and fast rules. An example is the gravamen of guilt beyond reasonable doubt. Instead of simply relying on their discretion, a judge uses jurisprudence to form a body of as yet unwritten legal standards to back up their decisions. To summarize, Dworkin champions the cause of Legal Naturalism: that laws must appeal to morality to have legal validity. Many of today’s penal laws can be said to espouse Legal Naturalism.