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Legal Research Resources for the Public: Types of Resources

Primary vs. Secondary Authority

  • Primary sources establish the law. They include cases, statutes, regulations, treaties, and constitutions. Relevant primary sources have the greatest influence on the outcome of any legal issue.
  • Secondary sources explain the law but do not themselves establish binding law. They include books and articles written about the law. Secondary sources can influence the creation and interpretation of the law, but are not determinative.

Primary sources, particularly statutes and regulations, do not provide explanations like secondary sources. Start your research with secondary sources to better understand the legal principles at issue and to locate additional relevant law.

Common Secondary and Primary Resources

Legal Encyclopedias

  • American Jurisprudence 2d ("AmJur") and Corpus Juris Secundum ("CJS")
    • AmJur and CJS are national encyclopedias. Each summarizes hundreds of legal doctrines, both at the state and federal level.
  • Michigan Law and Practice Encyclopedia 2nd
    • ​Discusses the basic elements of many subject areas pertinent to the practice of law in Michigan, including analysis of case law, statutes, rules, and other legal authority.

American Law Reports (ALR)

  • Articles in ALR, called "annotations," discuss the background, analysis, and relevant law of narrow legal topics.
  • ALRs refer to specific cases and other primary law.

Restatements of the Law

  • Restatements summarize the basic doctrine of a particular area of law as it stands at the time of publication.
  • Though still a secondary source, courts and legislatures tend to put more weight behind Restatements than other non-primary authorities.
  • Examples include Restatement of TortsRestatement of Conflict of Laws, and Restatement of Contracts


  • Treatises are books that outline the basic aspects of a particular legal doctrine, discussing that subject in greater depth than an encyclopedia or ALR.
  • Single-subject texts that are written as an overview for law students are called sometimes called hornbooks or practitioner treatises.

Law Journal Articles

  • Law journals (or "law reviews") are periodicals edited by law students and published by law schools, consisting of articles written by legal academics.
  • Law journals may cover a broad range of topics (e.g., Michigan Law Review) or be limited to a specific area of law (e.g., Michigan Business & Entrepreneurial Law Review).
  • Articles in law reviews usually include a summary of the legal topic at issue, as well as many citations to other secondary and primary legal sources. These features make law review articles excellent vehicles to expand legal research.

Case law refers to the reported decisions (or "opinions") of courts, which interpret existing law based on a specific set of facts. Judges look to past decisions for guidance in ruling on cases. 


Generally speaking, the decisions of higher courts are binding on lower courts in the same jurisdiction when similar issues are raised. When a court has jurisdiction over a matter, it is authorized to hear the case and possibly pronounce judgment. Federal courts and state courts have jurisdiction over different matters, while small courts (like probate or traffic court) have limited jurisdiction. [For a brief explanation of when court decisions are binding, see Mandatory vs. Persuasive Cases, by Barbara Bintliff (below). For a short explanation of the differences between federal and state courts, see Federal vs. State Courts--Key Differences, from FindLaw.] 

Case Names

A judicial opinion is referred to by its citation. A citation typically includes:
  • Party names (plaintiff/appellant v. defendant/appellee)
  • Number of reporter volume (the physical book in which the case is published)
  • Abbreviated name of reporter
  • Number designating the first page of opinion
  • Court and year in parenthesis

For example: Dixon v. Alabama State Board of Education, 186 F. Supp. 945 (M.D. Ala. 1960)

  • The parties in this case are Dixon and Alabama State Board of Education.
  • 186 is the volume of the publishing reporter.
  • F. Supp. is the abbreviation for the first Federal Supplement--the reporter in which the case was published.
  • The opinion starts on page 945 (of the 186 volume of the Federal Supplement).
  • The deciding court was the federal District Court for the Middle District of Alabama, abbreviated M.D. Ala.
  • The case was decided in 1960.
Sometimes cases are published in multiple reporters; these cases will have multiple ("parallel") citations. This is often the case with U.S. Supreme Court opinions. 
What a Case Contains

Published case law mostly consists of the decisions of appellate courts and courts of last resort (e.g., the Supreme Court). Since trial court decisions are not binding on other courts, they are usually not published. 

Judicial opinions typically include the following components:

  • Summary of the facts of the case.
    • What happened that instigated legal proceedings?
    • Some facts are material, and have an effect on the legal issues. Others are trivial, and do not.
    • The more facts that are similar to your situation, the more relevant a case may be to your research.
  • Outline of the legal proceedings leading up to the instant decision.
    • Who sued whom? What happened at trial? etc.
  • What legal issues are being decided by the opinion.
    • Even if the facts resemble your issue, the legal issue may be dissimilar.
  • The ruling of the judge or judges on each legal issue.
  • An explanation of why the judge ruled that way.
    • The reasoning of a legal opinion applies to the material facts of a case.

Statutes are laws passed by a legislative body, e.g., the U.S. Congress. Statutes typically go through the following publication life cycle:

  • A statute is initially published as a slip law, which is assigned a number and published individually.
    • e.g. Public Law 113-111
  • All the slip laws of a legislative session are compiled into a set and called session laws.
    • e.g. All the laws passed during the first session of the 112th U.S. Congress are published chronologically as session laws in the United States Statutes at Large, Volume 125.
  • Finally, statutes are compiled by general subject, resulting in a code of law
    • e.g. the United States Code is the official compilation and codification of the United States federal statutes.

There is more than one way to identify a statute.

  • Citation. Like cases, statutes have official citations based on their publication.
    • Federal statutes in the U.S. Code generally follow the same pattern: [volume number] U.S.C. [Section/subsection number] (year)
      • e.g. 23 U.S.C.  § 158 is located in Title 23 of the U.S. Code at section 158.
      • The U.S. Code is revised continually, so a parenthetical year may follow the section number.
    • State statute citations vary from state to state.
      • Some look similar to the U.S. Code citations, like Vermont.
        • e.g. 22 V.S.A. § 172 is section 172 of Title 22 of the Vermont Statutes Annotated.
      • Others, like Michigan, may follow a different form.
        • e.g. M.C.L. 750.103 is in the Michigan Compiled Laws, chapter 750, section 103.
  • Popular Name. Sometimes a statute is more commonly known by a popular name.
    • e.g., the USA  Patriot Act, the Taft-Hartley Act, No Child Left Behind.
    • If you are searching for the actual citation, Popular Name tables, like this one published by the U.S. House, are useful. A Popular Name table is also published at the end of the General Index in the print editions of the U.S. Code.
  • Subject. 
    • Statutory codes, including the United States Code and Michigan Compiled Laws, generally include a subject index at the end of each set. Look up a topic in an alphabetical list of subjects, and narrow the scope of your search through further subheadings.

Administrative regulations are promulgated by government agencies under the authority delegated by Congress. For more information about federal regulations and agency's rulemaking power, see Treatise Finder for Administrative Law.

The Federal Register is the chronological publication of proposed regulations, final regulations, and related materials, published weekly. The Code of Federal Regulations (CFR) is a subject arrangement of regulations. A regulation will be published first in the Federal Register and will later be included in the appropriate volume of the CFR.


Like cases and statutes, regulations are found through citations.

  • Federal regulations are cited according to Title Number, Publication Name, and Section.
    • e.g. 39 C.F.R. § 447.61 is in Title 39 of the Code of Federal Regulations, section 447.61.
    • If a regulation has not been published in the CFR yet, the citation may be to the Federal Register (Fed. Reg.)
  • Michigan regulations are cited according to Publication Name and Section.
    • e.g. Mich. Admin. Code R 325.13095 (or MI ADC R 325.13095) is section 325.13095 of the Michigan Administrative Code.

Other Administrative Materials

While many official documents produced by administrative agencies are found in the Federal Register, others are published by the agency itself. Administrative Orders and Decisions by agency heads are often more likely found on the agency's website.


A fundamental issue of legal research is knowing what jurisdiction is relevant to your case.

Federal vs. State

The two major court systems in the United States are the federal courts and the state courts. They each have their own precedents, hierarchy, rules, and other characteristics. 

  • Federal Courts are generally divided into District Courts, Circuit (Appellate) Courts, and the Supreme Court. See the Court Role and Structure guide by the U.S. Courts website for more information.
  • State court systems vary state-by-state. See this page by the Michigan Courts for an explanation of Michigan's current court system.