Law is the system of rules enacted and enforced by governments to regulate human behavior and create a society that functions well. It serves four principal purposes: establishing standards, maintaining order, resolving disputes and defending liberties and rights. Often, the precise meaning of law is debated. Some philosophers, such as Hans Kelsen, have argued that law is a system of normative science that seeks to define what should occur and establishes rules that individuals must obey. Other philosophers, such as John Austin, have argued that laws are commandments backed by the threat of sanctions from a sovereign and that people follow these commands because they believe that they reflect moral principles.

The law can be made by a legislative body resulting in statutes; by the executive via decrees and regulations; or, as in common law systems, by judges through precedent. Judges’ decisions have a greater legal weight in that they may be binding on lower courts. This principle is known as stare decisis, or the law of precedent. Private citizens, corporations and even international bodies can also create legal contracts that bind their members.

Many aspects of law are specialized, covering everything from property law to aviation law. Banking law, for example, is about financial regulation and imposes minimum standards to protect depositors from economic crises. Banking laws are based on regulatory principles that have been established by a combination of legislative and judicial decisions.

A more specialised area of the law is criminal law, which encompasses everything from theft to murder. Most nations have laws that impose minimum punishments for certain crimes and set standards for the conduct of trials. Civil and international law cover such things as contracts, property ownership, international treaties and the status of foreign nationals in a nation-state. These are based on principles that have been developed by legislators, lawyers and judges through a process of interpretation.

In addition, there is family law, which deals with marriage and divorce proceedings and the rights of children and the distribution of property. There is also environmental law, which tries to control pollution and the protection of endangered species. Lastly, there is transactional law, which covers business and money matters and biolaw, which is about the intersection of legal sciences and life sciences.

In general, the underlying philosophy of law is the belief that there are certain standards and norms that must be followed for society to function well. This is reflected in the fact that most countries have a constitution, which outlines the fundamentals of their legal system. Having a constitution is necessary to ensure the rule of law, although it does not prevent political instability, which can cause laws to be changed or rescinded. This is why revolutions against dictatorial or authoritarian governments occur in many places each year. The primary role of the law is to serve society, but the specific way that the law does this varies from country to country. It is important to understand the varying landscape of each nation-state, as it will influence the principal functions of the law and how that law is created, maintained and enforced.