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The Legal Research Process

The Hierarchy of Authority

When conducting legal research, it's important to understand the concept of hierarchy of authority.  In short, this refers to the weight of authority within the United States legal system. Researchers must understand the difference between persauasive vs mandatory sources of law.

Persuasive authority is NOT the law, but rather it leads you to the law (e.g., legal enyclopedias, law journal articles, treatieses, etc.). Secondary authority is always persuasive sources of law.  Do not cite secondary authority to support your legal research. 

Mandatory authority IS the law. It is binding and must be followed. All mandatory authority are primary sources of law. Mandatory sources of law should be cited to support your legal research. 

Keep in mind, however, that not all primary sources of law are mandatory authority because jurisdiction affects whether a legal authority is mandatory. 

Visit the link below for more information about authority in legal research.

The Hierarchy of Courts

There are three levels of court: 

  • Trial: Where the action is first brought. 
  • Appellate: Where the losing party at trial can appeal for a different result.
  • Supreme Court (Court of Last Resort):  The jurisdiction's highest court. An appellate case can appeal to this court.

Federal System Court Chain:

  • District Court
  • Circuit Court of Appeals
  • Unted States Supreme Court 

State courts have various names for their court levels.

For more information about court structure, visit the link below.

Developing a Legal Research Plan

What is legal research? In a nutshell, legal research is the process in which you identify the laws that apply to the facts of a case. 

Why is legal research so important? Knowing the process of legal research is essential in order to create legal memos, write case briefs, and establish a winning argument. 

When getting started with your legal research, have a research plan.

  • Write down all the facts of the case. Who are the parties involved? What is the desired outcome? 
  • Determine the legal issue. This is essential so you know what to look for in your research. 
  • Know the jurisdiction. Is it state or federal? What kind of law is involved (case law, statutes, etc.)? The jurisdiction will direct the focus of your research.
  • Start with secondary sources. Secondary sources often refer to relevant primary sources of law and can be very useful in your research.
  • Move on to primary sources of law. 
  • Use citator tools such as Shepard's (Lexis) or KeyCite (Westlaw) to follow the history of a case and to dertermine if the case is still "good law."
  • Finally, consult rules of  procedure, various practice materials, and other non-law related sources like statistics and directories.

Sources of Legal Reference

The Purude Global Library has lots of resources to aid you in your legal research. Since the Library subscribes to Westlaw Campus Research, many of the examples in this guide will refer to that specific legal database. Keep in mind that Westlaw is not the only electronic legal database, and law firms may subscribe to others, such as LexixNexis and Bloomberg Law.. 

Where shoud you begin your legal research? Start with...

Secondary Sources: These include American Law Reports (ALR), legal encyclopedias and dictionaries, law journals, restatements, and treatises They are a great place to start your research because they often cite primary sources of law that you can use.

Primary Sources: These include case law, statutues, and administrative regulations.

Key Numbers & Headnotes (available from Westlaw): The Key Number System is a master classification system of U.S. law. The Key Number system works in conjunction with Headnotes. Each headnote is assigned one or more topics and Key Numbers.This system makes it easier to find other cases addressing the same legal topic.

Citators: Make sure you're using "good law." Citator tools such as Shepard's in Lexis and KeyCite in Westlaw will flag a document and provide an brief explanation about the negative history of the case law.

Fore more in depth information, visit the link below from Westlaw.

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