Beware of treating this as a wishy-washy general idea about acceptable legal behaviour. There are some very specific meanings to the phrase.
Dicey proposed three aspects
(1) No person is punishable except for a distinct breach of law established in the ordinary legal manner before the ordinary courts of the land
- therefore there should be no 'arbitrary' justice
- behaviour should be prohibited in advance - not after the event
- people we think might have mischievous intent shouldn't be locked up because they might commit a crime (despite the exasperation of certain Home Secretaries that the Courts are reluctant to deport or intern people who aren't convicted of anything, but are clearly evil.)
(2) No person is above the law
- the ordinary law of the land applies to everyone, and as Barnett comments, "there must not only exist a system of courts available locally but the cost of having recourse to the courts must be such that there is real - rather than symbolic - access to the courts. For the law to be attainable, adequate legal advice and assistance must be provided at a cost affordable by all." (Once upon a time....)
(3) the general principles of the constitution are the result of ordinary cases in which rights have been determined.
- Dicey meant that in the UK we don't have special courts for Administrative Law, but the ordinary courts applied the same approach whether they were dealing with bureaucrats or ordinary citizens involved in disputes with other citizens. (Perhaps a bit quaint in this era of judicial review and multi-national corporations.)
NOTE - I've tried to be deliberately provocative - how who you respond to such opinions in an exam question? Reasoned evaluation is the key - and examiners look for it. You can practice by looking at newspaper headlines in the coming week - apply the "Rule of Law" to what the editor or the politician is arguing.
Allen and Thompson deal with the concept in Chapter three of their Cases and Materials on Constitutional and Administrative Law - 10th Edition
There are some useful cases to reflect upon - Prohibitions del Roy (1607); Entick v Carrington (1765)R v IRC ex parte Rossminster Ltd; R v Horseferry Road Magistrates Court ex parte Bennett; Phillips v Eyre; In re M (1993) - worth making brief casenotes on!
There are also some useful questions to consider as you revise.
Do reflect on how the concept of the Rule of Law relates to other constitutional principles.
There's an excellent book on the Rule of Law and related subjects by the late Lord Bingham.