Attorneys and paralegals conducting legal research have an ethical and legal duty to complete research as thoroughly and accurately as possible. Failure to conduct adequate research may constitute legal malpractice. It is essential to understand the difference between primary and secondary authority, as primary authority may be legally binding while secondary authority is not. A starting point in conducting research is often consulting legislative histories and law reviews, which then point to the relevant primary authority, such as statutes and laws.
Primary Authority Sources
Primary authority sources are official declarations created by the government from each of its three branches: executive branch, consisting of treaties and executive orders; legislative branch, consisting of constitutions and statutes; and judicial branch, consisting of cases. Some primary authority is mandatory, meaning that if it is applicable to the case, it is legally binding. However, some primary authority is merely persuasive. Mandatory primary authority includes decisions from the U.S. Supreme Court in both federal and state court for cases involving federal law. In addition, state supreme courts are mandatory authorities over all lower state courts.
Secondary Authority Sources
Secondary authority is used for persuasion only. It is not the law, but is often legal commentary or analysis of the law. Common sources are legal dictionaries, treatises, legal periodicals, hornbooks (study primers for law students), law reviews, restatements (summaries of case law) and jury instructions. In addition, primary authority that is outside of the case's jurisdiction is considered secondary authority.
Degree of Persuasion
When making arguments based on persuasive authority, it is important to identify the source's strengh of persuasion. Strong forms of secondary authority are court decisions not considered primary authority. For example, although a state law in Texas is not mandatory in another state, if the case in question has similar facts, the state law in Texas would be considered to have a high degree of persuasion. According to Barbara Bintliff, this is particularly relevant in cases where two states share similar doctrines, such as community property laws.
Primary authority should always be cited. You may also cite secondary authority as sources, depending on the source. For example, strong sources such as law reviews and treatises can greatly supplement your argument. Sources such as legal dictionaries can be used to learn about areas of the law and as a source for finding primary authorities; however, they are considered weak sources and should not be cited.