The Supreme Court has stated that Australia`s common law system is uniform across all states.  This can be compared to other jurisdictions such as the United States; which have maintained different common law systems in each state. While the Executive Council may seem like a buffer, the processes involved in invoking the Council ensure that ministers` actions are properly documented, legally and constitutionally valid and consistent with government policy. The language used by the legal system is almost a language in itself. In fact, it would be more accurate to say this in several languages, because there are different areas of law, each with its own terminology. The two main areas of law are, for example, civil law and criminal law. In civil law, there are other areas, such as: Business Law, Personal Injury Law, Labor Law, etc. Each area of law has developed its own terminology, although there are also terms that are widely used throughout the legal system. The Australian legal system is defined by the Australian Constitution. This establishes the lines of demarcation between the six states and the two territories and the federal government. In Australia, due to the federal nature of government, states and territorial governments have a good degree of control over the laws that exist in any jurisdiction.
Each state and territory, as well as the federal government, has a bicameral parliament (House of Representatives and Senate) in which legislative amendments are discussed and passed if there is a majority of votes in favor of the amendment. Federal laws may override state laws in certain circumstances, such as when it is in the interest of the nation as a whole. The Constitution can only be amended by national referendum, a provision inspired by the Swiss cantonal system. Before colonization, the only legal systems that existed in Australia were the various customary law systems that belonged to indigenous Australians. Indigenous legal systems were deliberately ignored by the colonial legal system and were recognized as legally important only to a limited extent by Australian courts in the post-colonial era.  The judicial system of each state and territory is responsible for the majority of the laws of each jurisdiction, most of which are based on the English common law inherited from Britain after the colonization of Australia. Parliamentary government means that executive government comes from parliament; Responsible government means that the executive government is accountable to Parliament. This is the central feature of a Westminster-style government that follows the model of the United Kingdom – unlike other systems of government where the executive branch is quite separate and is not directly accountable to the legislator – for example in the United States of America.
The English legal system was introduced by colonization in Australia. Upon their arrival in Australia, the settlers declared that the laws of England should apply immediately to all populated lands.  This statement was asserted, citing a legal fiction, that the Australian mainland was terra nullius; that is, lands that belonged to no one, because it was believed that the Aborigines who already inhabited the continent were not coherently organized to conclude a treaty with a single representation of their peoples.  The Australian legal system evolved from the legal system of Great Britain brought to Australia as part of the process of establishing a colony in Australia, beginning in the 1770s. Between 1855 and 1890, the British Parliament granted each of the British colonies in Australia a limited right to establish a local system of government, generally referred to as “responsible government.” As each of the colonies obtained this right, it was able to develop its own laws and legal systems to deal with its particular situation. Thus, the law and the legal system in each of the colonies began to develop separately. The ANU Library provides access to a number of legal databases. The following list is very selective and covers only the main sources of case law and legislation. A more complete list of legal databases can be found here or in the Business, Journal Articles and Legislation tabs for other databases covering this type of information.
Neither the Prime Minister nor the Cabinet is mentioned in the Constitution – the authors of the Constitution took its existence for granted, as did the various conventions of the Westminster system of government inherited from the United Kingdom. Four main principles are observed in the Australian legal system. It is the composition of the House that also determines who will form the official opposition. The party (or coalition of parties) with the most non-governmental members in the House of Representatives becomes the opposition party and its leader becomes the leader of the opposition.