This guide offers a basic introduction to legal research. This guide lists only freely available online resources. Depending on your research topic, you may also benefit from visiting or contacting your local law library in order to access additional resources.

Primary Law

Primary law is the actual text of the law as issued by official government bodies. We say "primary law" to distinguish from secondary sources (see below).

A basic understanding of the United States legal system is essential to knowing what to look for and where to find it. The legal system is actually three parallel systems–federal law, state law, and administrative law–operating under the authority of the US and state constitutions. The primary law of each system flows from four primary sources:

  • Constitutions (fundamental law of a nation or state).  Read the United States Constitution on the site of Cornell's Legal Information Institute.
  • Statutes (laws enacted by the legislature)
  • Cases (judicial opinions issued by courts)
  • Regulations and Adjudications (administrative agency materials).

In order to research effectively, you must determine if the issue involves federal or state law and what type of primary law applies.

Secondary Sources

To determine what law applies, you can turn to secondary sources. This catch-all category of legal materials is essentially everything that is not primary law. Secondary sources are materials that explain, analyze, critique or help you find the law. Examples are

  • Legal encyclopedias (comprehensive sets of brief articles on legal topics)
  • Treatises (scholarly legal publications that cover a large area of law in depth)
  • Law review articles (scholarly legal publications on narrow areas of law, often expressing the thinking of an expert with regard to very specific problems)

Many researchers recommend beginning with secondary sources because these helpful materials are a rich source of citations to the primary law.