Most commonly, the term constitution refers to a set of rules and principles that define the nature and extent of government. Most constitutions seek to regulate the relationship between institutions of the state, in a basic sense the relationship between the executive, legislature and the judiciary, but also the relationship of institutions within those branches. For example, executive branches can be divided into a head of government, government departments/ministries, executive agencies and a civil service/administration. Most constitutions also attempt to define the relationship between individuals and the state, and to establish the broad rights of individual citizens. It is thus the most basic law of a territory from which all the other laws and rules are hierarchically derived; in some territories it is in fact called "Basic Law". Key features The following are features of democratic constitutions that have been identified by political scientists to exist, in one form or another, in virtually all national constitutions. Codification A fundamental classification is codification or lack of codification. A codified constitution is one that is contained in a single document, which is the single source of constitutional law in a state. An uncodified constitution is one that is not contained in a single document, consisting of several different sources, which may be written or unwritten; see constitutional convention). Codified constitution Most states in the world have codified constitutions. Codified constitutions are often the product of some dramatic political change, such as a revolution. The process by which a country adopts a constitution is closely tied to the his
orical and political context driving this fundamental change. The legitimacy (and often the longevity) of codified constitutions has often been tied to the process by which they are initially adopted and some scholars have pointed out that high constitutional turnover within a given country may itself be detrimental to separation of powers and the rule of law. States that have codified constitutions normally give the constitution supremacy over ordinary statute law. That is, if there is any conflict between a legal statute and the codified constitution, all or part of the statute can be declared ultra vires by a court, and struck down as unconstitutional. In addition, exceptional procedures are often required to amend a constitution. These procedures may include: convocation of a special constituent assembly or constitutional convention, requiring a supermajority of legislators' votes, the consent of regional legislatures, a referendum process, and/or other procedures that make amending a constitution more difficult than passing a simple law. Constitutions may also provide that their most basic principles can never be abolished, even by amendment. In case a formally valid amendment of a constitution infringes these principles protected against any amendment, it may constitute a so-called unconstitutional constitutional law. Codified constitutions normally consist of a ceremonial preamble, which sets forth the goals of the state and the motivation for the constitution, and several articles containing the substantive provisions. The preamble, which is omitted in some constitutions, may contain a reference to God and/or to fundamental values of the state such as liberty, democracy or human rights.