Primary legal authorities are authorized statements of law issued by governmental bodies. This category includes court opinions, constitutions, legislation, regulations and rulings of administrative agencies and other similar documents that carry the force of law. Primary authorities can be either mandatory (binding) or persuasive (non-binding).
Deciding what constitutes mandatory authority involves a knowledge of which law-making bodies issue legal authority for a particular jurisdiction. The concept of jurisdiction initially involves a determination of whether an issue that arises in a particular geographic location is governed by state or federal law.
In addition to knowing what the law-making bodies are and their relation to each other (for example, rulings of higher courts within a jurisdiction are binding on the lower courts), one must make judgments as to the similarity of facts and issues to the circumstances in the problem that is being researched. Mandatory statutory authority must be followed; mandatory judicial authority must be followed under the principle of stare decisis, unless the court decides that changed circumstances warrant a different outcome. The doctrine of stare decisis encourages stability of the legal system and provides mechanisms for individuals to predict the outcome of their behavior. However, this goal is counterbalanced by the need for responsiveness to change. The result is a system that places a high premium on following established judicial precedents, but one that allows for change if it is necessary or desirable.
Persuasive primary authority can include court decisions of other jurisdictions, which do not have to be followed but which may be used as examples of good reasoning. For example, a decision of a Pennsylvania state court, or even of a federal court sitting in Maryland, would be only persuasive if the issue relates to Maryland state law. Searching for persuasive authority can be important if mandatory authority does not exist in a particular jurisdiction, or if the researcher wishes to look for arguments as to why existing precedents should be changed.
Secondary legal sources are descriptions of, or commentary on, the law. This category includes law review articles, treatises, Restatements of the Law, legal encyclopedias, and other similar items. Secondary sources can be used only as persuasive authority and vary widely in their relative weight as persuasive authority.
Statutes from jurisdictions outside the controlling jurisdiction are neither mandatory nor persuasive authority. Court decisions of other jurisdictions that are operating under different statutory frameworks cannot be used as persuasive authority. It is, therefore, important to determine the statutory framework under which cases in other jurisdictions have been decided.