"...people routinely use two quite different definitions, which they call “thick” and “thin”.
Thick definitions treat the rule of law as the core of a just society. In this version, the concept is inextricably linked to liberty and democracy. Its adherents say a country can be spoken of as being ruled by law only if the state's power is constrained and if basic freedoms, such as those of speech and association, are guaranteed. The “declaration of Delhi” drawn up by the International Commission of Jurists in that city in 1959 followed this line in saying that the rule of law “should be employed to safeguard and advance the civil and political rights of the individual” and create “conditions under which his legitimate aspirations and dignity may be realised.” Among other proponents of a thick definition are Friedrich Hayek, an Austrian economist, and Cass Sunstein of the University of Chicago. In their view, the rule of law includes elements of political morality.
Thin definitions are more formal. The important things, on this account, are not democracy and morality but property rights and the efficient administration of justice. Laws must provide stability. They do not necessarily have to be moral or promote human rights. America's southern states in the Jim Crow era were governed by the rule of law on thin definitions, but not on thick. "