The act of law-making itself must be governed by a higher law—a written constitution.
Manner and form of passing laws
A written constitution should prescribe the mechanism for passing laws. That process must provide for multiple readings, publicity, debate, and amendment.
Restriction of the laws can be passed
A written constitution should carefully prescribe the subject matter of laws that can be passed (with every purpose not expressly allowed being expressly prohibited) and should expressly prohibit the making of any laws which infringe prescribed rights or which have in the past been wrongly claimed under authorised powers.
To have a constitution that allows any laws to be passed is to grant the legislature unlimited power. For a government to be legitimately constituted under the natural law, it must be strictured in its law-making power. Otherwise legislators are set above the laws.
Britain, with its ‘unwritten constitution’, showed the depths of depravity to which an unfettered legislature can descend between 1945 and 1979. It was vogue during that period to abandon all principle, all rights, all considerations in favor of the overriding utilitarian goal, the greatest good for the greatest number of people. That wicked principle, upon which both socialism and communism are founded, led to 90 percent taxes (a complete disregard for property rights) and peacetime conscription of labor (slavery). At the end of that immoral experiment, Friedrich Hayek observed:
It turns out that the Americans two hundred years ago were right and an almighty Parliament means the death of the freedom of the individual … We can either have a free Parliament or a free people. Personal freedom requires that all authority is restrained by long-run principles which the opinion of the people approves. (Law, Legislation and Liberty: The Political Order of a Free People, Vol. III, 1979.)
The rule that judges must stand by what has already been decided (the rule of following precedent) is an important check on the arbitrary nature of the law-making power. Experience has shown that Common Law judges tend to deal with all but the most arbitrary discretions granted in legislation by quickly developing a body of constraining principles, which whittles down discretion to virtually nothing.
The tendency of judges to follow precedent is not solely due to their diligence. Like all good constitutional systems, the court system leverages off ambition to keep ambition in check. This is achieved through the use of appeal courts. Appeal court judges can wield power, but only if their decisions follow a consistent theme—otherwise lower courts can pick and choose which to follow. This forces appellate courts, in their natural ambition to control the lower courts, to maintain consistent bodies of principle. They realize that to imbue their authority with longevity, they must adhere strictly to the existing case law.