Legal positivism is best understood as a reaction to natural law theory. Legal positivists rejects the idea that law is teleological and that there is a morally good end that the law is striving to achieve. Legal positivists believe that morality is not a necessary component of a valid law, and that it is possible for immoral laws to be valid laws. To illustrate this point, we can look to the apartheid systems in Nazi Germany or South Africa as examples of legal systems that had immoral, yet valid, laws. Although both natural law theorists and legal positivists believe that there is a moral obligation to obey 'valid laws', the latter believes that the obligation to obey is based on the the fact that the law itself was validly enacted.
John Austin is one of the founding legal positivists. According to Austin, human behaviour is governed by three distinct directives. First, God's Law is a religious concept which is separate from human law. Some of God's laws are revealed, while the rest must be discovered through the index of utility to determine as best they can what God's commands are. Second, positive morality are rules that fall short of actual laws in that they are missing one or more of essential elements which makes a law valid. They include societal norms such as manners, customs, club rules, international law and English constitutional law. Third, positive law is a command, issued by superiors to subordinates, and backed by the threat of sanctions.
For Austin, a law is valid if the following criteria is satisfied:
(1) Law must be empirically provable;
(2) It must be a command, issued by superiors to subordinates, and backed by the threat of sanctions; and
(3) It must be created in accordance with the rule of the law making jurisdiction.
According to Austin, the role of the sovereign is to give generalized commands that apply to society. The role of the judges is to use these generalized commands and to make specific commands in accordance to the facts of a case. Judges are not part of the sovereign, but nonetheless has the power to make specific commands based on the authority delegated to them by the sovereign. Judge-made law (the common law) has the effect of a valid law so long as it does not conflict with positive law.
Case Study: Eldridge v B.C.
In the Eldridge case, John Austin would agree that the Medical and Health Care Services Act and the Hospital Insurance Act are valid laws because they were enacted by the legislature, whom the bulk of society is in the habit of obedience or submission to. However, Austin would not agree with the court's decision in applying the Charter to analyze the validity of theses Acts because in the eyes of Austin, the Charter is not a valid law because its purpose is to bind the sovereign.
Medical and Health Care Services Act and the Hospital Insurance Act
John Austin would likely agree that the Medical and Health Care Services Act and the Hospital Insurance Act are valid laws because the meet the Austin's three criteria mentioned above. First, it is clear that the Acts are empirically provable. Second, it is a command issued by superiors to subordinates, and backed by sanctions. In British Columbia, the sovereign is the aggregate body of the British Columbia legislature because the bulk of society are in a habit of obedience to them. Through the exercise of their law-making power, the BC legislature enacted the Medical and Health Care Services Act in order to regulate the health care system. Within this Act, the BC legislature delegated some powers to the Medical Services Commission to oversee the day-to-day operation of this social system. Among these powers is the Commission's discretion to determine which services would be covered under the Medical Services Plan. Specifically, the Act authorizes the Commission to determine which service is covered under the Medical Plan, and that the only restriction to its discretion is that the power must not be used in a manner that is contrary to section 7 of the Canada Health Act (Eldridge v British Columbia,  3 SCR 624 at paragraph 28). John Austin would reason that the Commission is a valid authority because it was created by the sovereign. By exercising their power, the Commission made a decision to not include sign language interpreters as a medical expense, which can be interpreted as a "command of the sovereign". Lastly, the Acts were created in accordance with the proper legislative process.
The Charter of Rights and Freedoms
According to the court in Eldridge, when a provision is in violation of the Charter, the court has the duty to ensure that the infringement can be demonstrably justified in a free and democratic society. In this case, the court found that the provision was contrary to the principles of fundamental justice because the failure to provide coverage for sign language interpreters was not a minimal impairment of the s.15(1) rights of individuals who are deaf (Eldridge v British Columbia,  3 SCR 624 at paragraph 94).
John Austin would disagree with the court's analysis because he would not recognize the Charter as a valid law. The issue with the Charter is that it fails Austin's basic element that a valid law must be a command issued by a superior to its subordinates. In this case, the Charter attempts to bind the authority of the sovereign, which is contrary to Austin's view that the sovereign cannot be bound by law. Although the Medical Services Commission's choice to not cover sign language interpreters infringes upon the rights of individuals who are deaf from fully benefiting from the health care system, Austin is not concerned with promoting equality of health care among citizens. Austin would likely state that the difference in access to health care, although unjust, is still valid law. As previously mentioned, legal positivists accept the fact that valid laws can co-exist with unjust valid. Under these circumstances, Austin would classify the Charter under positive morality since it purports to bind the sovereign.