Our laws themselves are compromises between the views, principles and interests of several groups, often satisfactory to none. So we cannot say in advance that a set of laws will be complete and not contradictory. Circumstances may occur to which the laws apply, but for which the rules are not intended. Or unforeseen circumstances will occur to which the laws do not directly apply. This points to the need for a new law or new judgments about the application of existing laws.
Human laws are human creations.
And humans individually or collectively may err. The formulation of laws and rules and principles by people introduces the possibility of error. Most law makers, following the direction of their parties, typically do NOT read in full the laws and regulations they pass. In consequence, lawmakers do not know their own intent in passing a rule. The precise interpretation of an imprecise rule or law may be left to courts or judges.