Sources of law is a legal term that refers to the authorities by which law is made. There are a number of different sources that are used to define the creation and force of law, though not all are used equally. Some examples of sources include legislation, government regulation, court decisions, and custom.
Constitutions are legislative documents that are a primary source of law in many regions. They are typically the highest law of the land, meaning that state or regional laws cannot conflict with a constitutional statute. States may also have constitutions, which local laws cannot conflict with. Most modern countries have a written constitution, though some, like New Zealand and the United Kingdom, have constitutions that are uncodified, meaning that they have grown and changed over time and include both written and unwritten sources.
Common law is one of the major sources of law that has been in use for nearly 1,000 years. This type of law is based on judges' decisions as well as legislation deeming certain actions illegal. Common law may dictate the specific laws and penalties of certain crimes, including murder, rape, and theft. One common concept in this important source of law is that of precedent, which suggests that future courts follow the rulings of prior courts on specific issues.
In addition to constitutions, many governments have the right to create legislation and statutes. Even local organizations such as city councils have the power to create ordinances that affect citywide behavior. These statutes and ordinances are often recognized as sources of laws.
Although discussions of sources of law generally revolve around regional law, there are other types of rule systems and guidelines that cite specific sources. Religion, for instance, often draws on specific important texts and laws handed down by elders in the organization to create codes of behavior and permitted actions. Natural law theorists argue that some laws are built into the fabric of universe itself, guiding both behavior and scientific principles, such as the inability to travel faster than the speed of light.
Custom-based sources of law generally rely on an existing behavior in a population. If, for instance, the entire workforce of a town takes a certain day off work each year, the city council could use that custom to create a law calling that day a public holiday. This type of law dates back at least until the Middle Ages in Europe, when local law would codify rights and responsibilities based on customs that had existed for generations.