As I have blogged in several posts, the citizen is governed according to the principle "whatever is not explicitly forbidden is permitted," while a cop or bureaucrat, according to the principle "whatever is not compulsory is implicitly forbidden."
Citizens are members of a civil association governed by adherence to the same system of law; cops are part of an enterprise organization of the executive branch of the state governed by a common purpose.
Regarding the citizens, the law, of all 3 kinds of natural made by God, positive made by the people or legislature, and administrative made by the authorities, is addressed to the judges and promulgated to the people. Of course, natural law need not always be explicitly promulgated, since it is written on people's hearts, and everyone knows it. Moreover, the punishment can always be guessed to be proportional to the crime; however, if in certain cases such punishments are awkward or inconvenient to deal, a penal code even for natural law needs to be promulgated. As such, laws are incentives to the people; they say: "if you want to avoid being punished, do not murder."
But it is judges who decide syllogisms such as:
1) Major premise, law: If anyone murders, then he shall be punished with 10-20 years in prison.
2) Minor premise, facts: Smith murdered Jones.
3) Conclusion, judicial verdict: Therefore, Smith is to be punished with 14 years in prison.
The truth or falsity of the minor is decided by the jury. The major on its own has no power; only the conclusion, the sentence does. The laws are inputs to a judge. The syllogism is an essential step, even if "obvious." The judge has some discretion to tailor the punishment to the specifics of the case, but any sufficiently wise person can understand why a competent judge decided in a particular manner. The verdict then orders the cops and jailers to punish the criminal. We can say that law is an indirect command to the executive branch to inflict punishment.
And this is the essence of the rule of law: that cops and bureaucrats must always await orders from a judge before they can act. They are fundamentally unfree; we can even say that they trade their freedom for power. Unlike private citizens, they cannot act in search of their own happiness: they are obliged mostly just to sit there and do nothing until a judge has need of them. But also unlike private citizens, when they finally spring into action, they do something that no citizen can lawfully do.
Laws then are incentives to the people, and indirect, through the mediation of the priestly judicial aristocracy that uses them in legal syllogisms, commands to the enforcers.
There are two types of "rule of law" then.
One forbids a finite list of things to a citizen with all other things remaining permitted. It involves things like private judiciary, due process, and lack of dirty tricks such as bills of attainder.
The second requires a finite set of duties of a cop with all other things staying forbidden. It means subservience of the executive branch to judges directly and to the law indirectly. Any exercise of police power must be done according to "the book" and formally justified.