While both types of law entail some differences, they are ultimately both based on the same principles. Common law is based on the decisions of past judges, and statutory laws are based on statutes enacted by a legislative body. While common law is still being developed today, it is not a cause for concern because it is not costing the state any money. In contrast, statutory laws are developed by government agencies, and are organized into law codes. The latter covers areas where common law does not apply, and it is more likely to be applicable in those cases.
Common law derived from ancient maxims, and was often a counterpart to Roman law. Throughout the 17th century, English courts recognized certain types of action based on common law principles, such as debt and detinue. This practice remained in effect until the mid-18th century, when courts adopted statutes. Although the two traditions inherited some similarities, they differ primarily in the fundamental principles of reasoning and decision-making. In the 17th century, Lord Chief Justice Edward Coke published his Institutes of the Lawes of England, which is still widely taught in law schools.
Statutory law is the result of legislative decisions and the decisions of administrative agencies. While common law is a form of constitutional law, it often contains elements that are different from those in statute law. For example, statutory laws may make significant changes in the way people live their lives. In Canada, for example, federal legislation to recognize same-sex marriage was prompted by the Ontario Court of Appeal. Ontario had already ruled that the common law definition of marriage was in conflict with the Charter.