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Law 627: Legal Research: Unit 3: Courts

Unit 3: Overview

This page will provide you with an overview of how American courts are structured and how the concept of 'authority' works with regard to legal information.

At the end of this lesson you should be able to:

  • Understand the basic structure of federal and state courts
  • Articulate the difference between mandatory (binding) and persuasive law
  • Explain how to determine the value of an individual case or citation


Legal Authority
That which can bind or influence a court. This includes case law, legislation, constitutions, administrative regulations, and writings about the law. Legal authority can be mandatory or persuasive.

  • Mandatory (Binding) Authority: Authority that a given court is bound to follow. Mandatory authority is found in constitutional provisions, legislation, and court cases. Compare with persuasive authority.
  • Persuasive Authority: Law or reasoning which a given court may, but is not bound to, follow. For example, decisions from one jurisdiction may be persuasive authority in the courts of another jurisdiction. Compare with mandatory authority.

Court Opinion
The written expression of the reasons why a decision was reached in a case.

The power given to a court by a constitution or a legislative body to make legally binding decisions over certain persons or property, or the geographical area in which a court's decisions or legislative enactments are binding.

Stare Decisis (Precedent)
The legal doctrine that states when a court has formulated a principle of law as applicable to a given set of facts, it will follow that principle and apply it in future cases where the facts are substantially the same. It connotes the decision of present cases on the basis of past precedent.

Supreme Court (court of last resort / last instance / final determination)
(1) The court of last resort in the federal judicial system (the U.S. Supreme Court also has original jurisdiction in some cases); (2) in state judicial systems, except New York and Massachusetts, the highest appellate court or court of last resort.

Intermediate Appellate Court
A court having jurisdiction to review decisions of a trial-level or other lower court. Not all jurisdictions have an intermediate appellate level.

Thinking Outside the Box(es)

Think about your family tree. Do you find where someone "sits" on the tree influences how you value his or her opinion? As a child, were your parents' rules authoritative in your own home? How would have those same rules been seen by your cousins?

It can be helpful to think of courts and their authority in this same manner. The direct line above a jurisdiction is its mandatory authority. All other authorities will be persuasive. Even this persuasive value can vary depending on the relationship. The further from one's own branch, the less value it may be perceived to have, in the same way you might value your peer (who is on your level) more than someone much younger (who may not have tackled the world yet in the same manner as you).

image of family tree with Supreme Court at trunk representing parents, the appellate courts as branches, and trial courts as leaves


Understanding Courts and Legal Authority

The United States has a common law system, which means that courts decide disputes and, in so, doing develop legal principles that apply to future similar cases. The prior decided cases create what we call precedent. Common law precedent operates within the jurisdiction from which it was issued as mandatory (or binding) authority. Other jurisdictions may look at these decisions persuasively, but are not bound to the decisions outside their jurisdiction.

Since courts are bound to the precedent of their jurisdiction when settling legal disputes, it is important for legal researchers to understand the basic structure of the court system and the hierarchy of authority in the respective jurisdiction.

Determining whether a given case is mandatory is a necessary skill for any legal researcher. It can be tricky and it may take a bit of time and practice to hone that skill. Use the images below to test yourself and see how well you can apply the concept.


Which court has jurisdiction?

It is important to understand the relationship between federal and state court systems. In the United States, the federal Constitution reserves certain powers for the federal government. All other governmental functions are left to state control. Within the federal and state systems are further geographic subdivisions, as well as hierarchical layers. All of this relates to a more complex aspect of law called jurisdiction.

You will study jurisdiction in detail in first-year Civil Procedure. For now, it is simply enough to remember the importance of understanding within which system (federal or state) and which subpart (for example, the Fourth Appellate District in Illinois) your research problem takes place. You will also need to understand the basic hierarchy within each system for the purpose of evaluating the authority of a given source.

United States (Federal) and Illinois (State) Jurisdiction Maps

Below are maps showing the geographic areas covered by United States (federal) and Illinois (state) courts. Click on the image to open the court website for more information.

To illustrate, the following jurisdiction applies to Champaign County, Illinois: 

U.S. Federal

U.S. Supreme Court court of last resort / last instance / final determination
U.S. Court of Appeals for the Seventh Circuit stand-alone intermediate appellate court reviewing trial decisions from all federal district courts in Illinois, Indiana, and Wisconsin
U.S. District Court for the Central District of Illinois one of three federal trial courts in Illinois (the others being the U.S. District Courts for the Northern District of Illinois and the Southern District of Illinois)

U.S. Federal

U.S. Courts of Appeals (intermediate appellate) and U.S. District Courts (trial)

Map showing the 11 Numbered Federal Circuit Courts of Appeal and their included district courts

Illinois (State)

Illinois Supreme Court court of last resort / last instance / final determination, unless the U.S. Supreme Court agrees to review an Illinois state court decision on appeal (when at least one matter of federal law is at issue)
Illinois Appellate Court, Fourth Appellate District unified intermediate appellate court, divided administratively among five (5) districts; the Fourth Appellate District addresses appeals from the Sixth Judicial Circuit, which covers Champaign County
Illinois Circuit Court, Sixth Judicial Circuit trial court that covers Champaign, DeWitt, Douglas, Macon, Moultrie, and Piatt counties

Illinois (State)

Illinois Appellate Court (organized into Five (5) Districts) (intermediate appellate)

Map of the 5 Illinois Circuit Courts of Appeal

Illinois Circuit Courts (trial)

Illinois map of state court jurisdictions