These are sets of rules and customs outside the law and which can be stated with much precision as the rule of law. These conventions are created by those in authority and those who put the law into operation. Their precedents are followed by officers and when they become old enough, they become the tradition which are respected and followed. Dicey named these as the “rules and conventions of the constitution”. A large part of the British constitution depends on conventions. Constitutional conventions enable the constitution to bend without breaking and adjust itself to changing needs without a complete overhauling. It also helps the constitution to work smoothly.
This source involves laws prescribed by legislation. Legislative decisions can include Acts of parliament, statutes of great antiquities, and enactments of subordinate law-making bodies such as bye-laws passed by local authorities and orders made by ministers. Statues or Acts of parliament are the most important sources of British constitution. The Nigerian defunct National Assembly passed some laws between 1979 and 1983. Legislative decisions are called statutes.
These are previous decisions of courts of law. There are often laws and customs of the people which have received judicial recognition in the reason given by judges for their decisions in particular cases. They are also known as the law made by judges through their interpretation.
These involve the writings and opinions of renowned academicians. But these opinions do not become laws until they are accepted as such by the courts. Just like judicial decisions, academic writings can be evidence of customary law and can also play subsidiary roles in developing new rules of law.
In all countries, written laws do not normally cover or regulate all social, economic and political behaviour. A parliament therefore passes some more fundamental laws which cover certain loopholes found in the constitution. These promulgated laws are called organic laws and they differ from other laws in that they deal with basic organisations and procedures of government rather than with specific governmental policies as in the case of ordinary laws. Organic law may sometimes establish specific agencies such as the National Economic Council or may even provide for instance, that judicial power of the state be vested in the Supreme Court.