Law is the set of rules that a government or society establishes to regulate behavior and enforce rights. The precise nature of law is a matter of longstanding debate, involving both theoretical and practical issues. The theory of the Rule of Law, for example, involves the idea that laws should be generally applicable rather than targeted at specific individuals or groups and that they must be promulgated well in advance so that people can plan to comply with them.
The idea of the Rule of Law is not only an important theoretical concept but also a central part of how many states, especially emerging ones, operate. Often it is argued (as in Barro 2000) that a new state needs Rule-of-Law institutions such as effective courts and commercial codes before it can attract the investment that is essential for modern governance.
The most fundamental tenets of Law are those enshrined in natural-law theories. This philosophical approach asserts that human beings are born with certain inherited principles, or “moral truths”, that serve as guides to behaviors and which distinguish right from wrong. These innate moral principles, in turn, give rise to legal prohibitions, for example, the prohibition against murder.
Aquinas, one of the earliest and most comprehensive proponents of natural-law thinking, argued that valid positive law could be derived in two ways. First, it could be deduced by a kind of immediate deduction from the moral principles, such that there was a direct correspondence between them, and second, it could be derived by a more indirect process which he called determinatio. This involved determining the way in which a general moral principle like that of not killing would, in particular circumstances, facilitate human coordination and thus justify the corresponding legal prohibition against murder.
For many, this is a plausible explanation of the origins of law. However, there are problems with the implication that a legal system should be designed to maximize efficiency. One obvious problem is that there is always a tension between the desire to avoid distortions and the necessity to be flexible enough to adapt to changing conditions.
Nonetheless, despite these challenges, the idea of the Rule of Law remains attractive for many. For one thing, it takes some of the sting out of being ruled by a political community, generating what Fuller (1964) called a bond of mutuality that mitigates the asymmetry between ruler and ruled that necessarily accompanies politics. For another, it provides a framework of predictability that reduces the uncertainty that would otherwise undermine confidence in the system. This in turn reduces the need to use coercive power to enforce the law. This, in turn, reduces the threat of violent uprising by disgruntled members of a community. Law therefore serves a number of vital purposes, which include setting standards, maintaining order, resolving disputes and protecting liberties and rights.