I have had occasion to ponder the basis of the legal systems used in many Commonwealth countries and also in other former British colonies. This basis is often called “common law”. Common law is basically law as defined by decisions made by courts and similar bodies which enter into the system as precedents. These precedents then have force of law until countermanded by a legislative action or further precedent. The alternative is that all laws must be made by a governing body such as a legislature of king. Upon reflection, it is not clear to me that common law is necessarily a good solution
First, let me examine the reasoning behind common law. At the most basic level, the theory is that any particular set of facts should be treated the same whenever circumstances are the substantially similar. Thus, the presence of duly executed deeds must be accounted for the same way in any land ownership dispute. Also, in the case of a contract dispute, like wording should be treated the same regardless of the parties or specific contract involved. This is, at its heart, a fairness doctrine.
There is also an advantage to the common law system in that neither the legislative nor executive branches of government need be concerned about minor matters. Instead, a collection of precedents is built up over time based on actual disputes. Situations that never give rise to disputes never require intervention at all and there is no need for any branch of the government to attempt to anticipate such cases for when a dispute occurs, a precedent will be set.
The primary disadvantage of the common law system is not immediately obvious. However, by examining actual common law legal systems in use today, the disadvantage becomes clear. As time passes, the number of precedents that must be considered increases. For instance, in Canada, it is not unheard of for a case decided in England a century before Canada existed to be considered as a precedent. Even seemingly simple disputes can involve extended wrangling over just which precedents are relevant. This leads to an ever increasing cost to employ legal advice in a great many circumstances, thus taking legal recourse out of reach of an increasing number of citizens. It also increases the likelihood that errors will be discovered on appeal or that inconsistencies must be reconciled.
Common law systems also commonly suffer from jurisdictional interactions. A decision made by a court in one jurisdiction is often not binding on courts in other jurisdictions, even within the same legislative domain. This complication is particularly noticeable in the United States with its proliferation of courts at different levels of the authority hierarchy.
Essentially, a common law system, while appearing inherently fair by nature, yields an increasingly complex code of laws (the “common law”) over time. As the complexity increases, the ability of the regular citizen to understand it, and consequently to comply with it. Without some mechanism for removing precedents from the common law, there is no way to fix the problem.
So far, I have discussed the common law as though it exists in a vacuum. Indeed, it can do just that. An entire legal code for an entire country could start from a series of decisions made by judges who have no guidance whatsoever from any higher authority. This is, however, unlikely. Most nations have some sort of constitution that serves as an ultimate authority on all legal matters. Those that don’t usually have a collection of royal decrees or other laws set by legislative or executive branches of government. Further, legislation is often introduced to clarify or otherwise countermand precedents from the common law. Basically, it is unlikely to encounter a purely common law system.
So what is the alternative to common law? Basically, courts are required to make determinations based on actual laws passed by the legislature or enacted by the executive branch. When there is no guidance from such laws, the court will make a determination for that case based on whatever reasoning it chooses but that decision will not affect any future decision. There is no such thing as a precedent in such a system. Thus, the legal code only gains complexity through legislative or executive action. Obviously, this can lead to different courts making different (but legal) decisions based on the same facts. This can be regarded as inherent unfairness. However, such a system also means that the code of laws in force tends to remain much smaller. Additionally, such a system does not preclude the existence of a constitution or similar supreme authority.
A case can be made for either of the extremes and also for any number of balances between the two approaches. It is not clear that any one approach is necessarily better than any other. On the one hand, common law would seem to be fairer by nature but on the other hand, statutory and regulatory law (law created by the legislature or executive branch respectively) would seem to reduce the complexity of the legal code in the long term. Which is better depends on which of those two results is more desirable.
I should note that the concepts of common, statutory, and regulator law are completely orthogonal to other concepts, such as presumption of innocence or presumption of guilt.