Domitus Ulpianus said: "Justice is the constant and perpetual will to give to every man his due." Justice is what allows a society to operate and function. It is supported and enforced by a system of rules known simply as law, officially recognized and imposed on states to regulate behavior. Some form of law has always existed in human history, whether in unwritten customary form or in written format such as a constitution (Milgate P, 2013). Law and legal systems around the world have developed throughout history to the point that there are many different categories and subcategories of law. In modern Australia, the legal system was modeled on the English system. It is a combination of statute and common law. Australia adopted these laws from England at the time of colonisation, when Captain Phillip declared the land "terra nullius" claiming it under England. Despite the fact that both common law and statue law are enacted in parallel in Australia, they are quite different. Common law and statutory law are both created and modified in different ways, have distinct advantages and disadvantages, are effective and ineffective in certain situations, and have developed into their contemporary forms through different paths. Through these two laws lies the basis of modern Australian law (Legal System, 2014). Common law, while having a slightly ambiguous meaning, is used to define a system known as case law in which the law develops through the decisions of courts and judges. Common law has existed in England since the Middle Ages, when the church, landowners, barons and other appointees of the king formed the court and administrative bodies. During their individual reigns, William the Conqueror and Hen...... middle of paper ......er. Parliamentary documents are written in complex terms and their meaning can often be confusing. Common law can be used to clarify or interpret laws. Wherever there is dispute about the meaning or application of legislation, a court can decide and resolve those issues. For example, if a law states that councils must approve the removal of trees. People may argue about what species of trees or whether the tree is dead or not. Judicial interpretation can make decisions on these matters (Milgate P, 2013). Overall, the law determines how a society or state acts by dictating what people can and cannot do. However, the law has changed over time and differs from place to place. In Australia, both Common Law and Statute law are implemented in the legal system. They serve as sources for the contemporary law of Australia as they were received from the English legal system.