The concept of justice, or law, comes into being as soon as any kind of social relationship is created. For example, Robinson Crusoe, living alone, had no need for laws. There was no one with whose rights he could interfere by exercising his own freedom of action. But as soon as his man Friday appeared, there was a chance of conflict between his rights and those of his servant. Law then became necessary.

The purpose of law is to set down and to make clear the social relationships among individuals and, between the individual and Society. It tries to give to each person as much liberty of action as fits in with the liberty of others.

Laws usually develop from the customs of a people. The earliest known system of laws was formed about 1700 B.C. by Hammurabi, King of Babylon. He set down a code, or complete list of laws, that defined personal and property rights, contracts, and so on.

Customs grew into laws because the force of government was put behind them. Later, laws grew from decisions that were made by courts and from books in which lawyers wrote down what had been learned. Still later, laws were set down in statute books, or codes, by kings and legislators.

The Romans were a great law making people and the law books of Emperor Justinian, who lived from 527 to 565, summed up 1,000 years of their working-out of laws. During the Middle Ages, people’s actions were largely governed by the church, which developed a body of laws called canon law.

In the twelfth century, the Roman law began to be studied in Italy and gradually spread to the rest of Europe. Thus, a body of laws, based on the Roman law, developed into what is called civil law, as contrasted with the canon law. At the same time, the courts of England were making many decisions about law, and from these grew up a body of laws called the common law.

In 1804, Napoleon put into a book all the civil laws of his time. This Napoleonic Code is the foundation of the law on the continent of Europe and in Central and South America. The common law system, which developed in England, is the basis of the law in the United States, Canada (except Quebec), Australia, and New Zealand.