At the top of the reporter page you will see the citation to the case, including any parallel citations (citations to the same case in other reporters). Then you will see a short summary of the case (the syllabus), including how it got to the court which has issued the opinion you are reading, and the holding(s) on the point(s) of law in the opinion you are reading. After the syllabus, you will see the headnotes discussing the point(s) of law in the case in the order in which they appear in the case, as well as the topics and key numbers which you can use to find other cases on the same legal issues. Then you will find the actual text of the opinion.
One important note: the headnotes and summary are NOT written by the court; they are written by West editors. Therefore, you should never cite to a case based on what you've read in the syllabus and headnotes; you must read the case and cite to the language written by the court.
Cases start out as bench opinions, then slip opinions, then preliminary prints, then published cases. To know what kind of opinion you are reading, see Information about Opinions from the U.S. Supreme Court.
Cases are opinions, written by judges, which resolve disputed legal issues (as opposed to disputed factual issues). Researching cases is important because of the doctrine of stare decisis, or precedent. Under the principle of stare decisis, courts are bound to follow the rulings of law from previously decided cases in the same jurisdiction to similar cases currently before the court. For the legal researcher, reviewing cases from a court will help you determine how the court will rule if given a similar factual situation. In the U.S. system, the only published cases you will find are from intermediate appellate courts and Supreme Courts. Most trial court decisions are not published.
Cases are published in chronological order in reporters. There are two different categories of reporters which you need to know: official reporters, which are usually published by a governmental entity; and unofficial reporters, which are published commercially (usually by either West or LexisNexis). To find a case in a reporter, you will need to know its citation. A case citation includes the name of the case, then the volume number of the reporter containing the case, the abbreviation for the reporter, the first page of the case, and the year of the decision. For example:
P.G.A. v. Martin, 532 U.S. 661, 121 S.Ct. 1879, 149 L.Ed. 2d 904 (2001).
To find the text of this case, you would go to Volume 532 of the United States Reports (the official reporter of the U.S. Supreme Court), page 661. You can also find the case in Volume 121 of the Supreme Court Reporter (West's unofficial reporter) or in Volume 149 of Lawyer's Edition (Lexis's unofficial reporter). You will often see multiple citations to the same case, called parallel citations, when it is reported in multiple reporters.
Cases are published in order, based on the date they were decided, and not by subject. Unfortunately, however, the research projects you receive usually will be asking you to research a legal issue (a subject). Therefore, you need an index to the reporter system. This is where West's National Digest System and Topic and Key Number System come in handy. West publishes unofficial reporters as part of its National Reporter System, with a goal of including every reported case from every jurisdiction. For state cases, West publishes seven Regional Reporters which each include cases from several states. West publishes a map that shows which states are in which regional reporters. Note that these do not always make geographic sense - for instance, Oklahoma and Kansas are listed as "Pacific" states.
West's Digests provide an indexing function for the cases in the National Reporter System, enabling a researcher to locate cases by subject from any jurisdiction. They also provide an abstracting function, giving researchers short summaries of the points of law discussed in the indexed opinions.
The Digest System sub-divides the law into over 450 Topics, which are broad legal issues, and then further sub-divided into Key Numbers, which are assigned to specific legal issues within the broader issue. Topics and Key Numbers are consistent throughout West's System - the same subject arrangement is applied to all cases from every jurisdiction, so that if you find a case from one jurisdiction that discusses a legal issue you are researching, you can use the topic and key number for that isssue to find other cases from other jurisdictions that discuss the same issue. Remember that you need to know both the topic AND the key number to search the Digests.
West employs attorneys who read each case, identify the point(s) of law discussed, summarize the point of law into a headnote (a paragraph summary of the point of law) using consistent legal terminology. Each headnote is then assigned to at least one topic and key number. These headnotes will appear in the digest under the appropriate topic and key number and at the beginning of each case as it appears in a West reporter.
Therefore, headnotes act as the bridge between the Digests and Cases: you can use the headnotes from a case you have and look in a Digest under the same topic and key number for similar cases; alternatively, you can start with the Digest, look up the subject by topic and key number, and then find cases by reviewing the language of the headnotes that appear in the Digests.
Cases may appear in more than one Digest (e.g. California cases appear in both the California Digest and in West's Pacific Digest). There are Digests that correspond to the Atlantic, North Western, Pacific, and South Eastern Reporters; if no Regional Digest exists for the state you are researching (e.g. Texas and Missouri in the South Western region, Illinois in the North Eastern region), you would have to use the state's Digest. You should always start your research by looking in the Digest that covers the smallest number of jurisdictions possible. For example, if you're researching California cases, it's better to use the California Digest because the Pacific Digest includes cases from other jurisdictions (e.g. Oklahoma, Oregon) that probably won't be relevant to your research.