Identifying the rules that apply to a particular legal issue in your jurisdiction requires legal research. The legal research process involves not only locating legal authorities, but also determining their relevance.
Legal researchers utilize two types of authority, referred to as primary and secondary authority.
Primary authority is the law, which includes constitutions, statutes and ordinances, rules and regulations, and case law. These authorities form the rules that courts follow.
Secondary authority is not the law. Secondary authorities such as legal dictionaries, encyclopedias, journals, and books and treatises, are valuable to your research process because (1) they explain and analyze the law, and (2) they help you identify relevant primary authorities. Great places to start your research include the two national legal encyclopedias (American Jurisprudence (Am. Jur.) and Corpus Juris Secundum (C.J.S.)), a state specific legal encyclopedia like South Carolina Jurisprudence, or a journal article published in the South Carolina Law Review, or other academic law journal, but you would not cite these resources as the law.
Authorities that courts must follow are called mandatory (or binding) authority.
Authorities, i.e. case law, that courts may follow but are not required to are called persuasive (or non-binding) authority.
Secondary authority is always persuasive because it is not the law.
Primary authority (the law) may be mandatory or persuasive depending upon:
State Law Issues
State courts apply state statutes and regulations and follow precedent from that state. For example, South Carolina courts must apply South Carolina statutes, regulations, and case law. If a South Carolina court has not ruled on a particular legal issue, it may be persuaded by a decision from another state.
For example, a South Carolina court may be persuaded by a Georgia case. The Georgia case is considered primary authority (is it the law) but persuasive only (from another state) by that South Carolina court.
Federal trial courts, called district courts, are organized into eleven numbered circuits, the District of Columbia Circuit, and the Federal Circuit (for a total of 13 districts). For issues of federal law, federal district (trial) courts apply federal statutes and regulations and precedent from the Court of Appeals in their respective circuits.
South Carolina federal district (trial) courts are in the Fourth Circuit. If the Court of Appeals for the Fourth Circuit has not ruled on a particular legal issue, it or a federal trial (district) court in the Fourth Circuit may be persuaded by a decision from a different federal circuit.
For example, courts in the Fourth Circuit may be persuaded by a federal case from the Fifth Circuit. That Fifth Circuit case is considered primary authority (it's the law) but persuasive only (from another Circuit) by courts in the Fourth Circuit.
United States Supreme Court decisions are mandatory on issues of federal and constitutional law for all state and federal courts.
Within a particular jurisdiction (state or federal), whether a decision (case) is mandatory or persuasive depends upon the level of the court that decided it. State and federal courts typically follow the court structure depicted in the diagrams below. Trial court decisions are not mandatory for any court. Intermediate appellate court decisions are mandatory for the trial courts below. Decisions of the highest appellate court or court of last resort are mandatory for both the intermediate appellate courts and trial courts below.
The South Carolina Supreme Court is our court of last resort. Its decisions are mandatory for our intermediate appellate court, the South Carolina Court of Appeals, and all South Carolina trial courts. Decisions of the South Carolina Court of Appeals are mandatory for South Carolina trial courts only.
Decisions of the South Carolina Supreme Court may be heard on appeal by the United States Supreme Court only if accepted via a petition for writ of certiorari on an issue of federal law or the U.S. Constitution.
The decisions of the United States Supreme Court are mandatory for all United States Courts of Appeals and all United States District (trial) courts. The decisions of each United States Court of Appeals are mandatory for the United States District (trial) Courts within its Circuit only.
Decisions of U.S. Courts of Appeals may be heard on appeal by the United States Supreme Court only if accepted via a petition for writ of certiorari on an issue of federal law or the U.S. Constitution.
With a basic understanding of the structure of the U.S. legal system, the available sources of law, and the application of weight of authority, you will be prepared to you find as you conduct your legal research. The diagram below depicts the steps for determining weight of authority discussed above.