If the issue you are researching involves a statute, regulation, or court rule, an efficient strategy for finding relevant cases involves checking the Notes of Decisions (Westlaw) for that statute, regulation, or court rule.

Notes of Decisions are like a highlights reel of cases applying or interpreting the statute; they are example cases selected by the editors of Westlaw that address certain topics. Because the cases included in the Notes of Decisions and Case Notes are selected by editors, it is a good idea to keep in mind that this is not a comprehensive list. 

Notes of Decisions are selected from among the Citing References. Citing References consists of all cases that cite a statute, regulation, or court rule. Notes of Decisions are thus a subset of the Citing References.

After you find the statute, regulation, or court rule on Westlaw, click on the tab for "Notes of Decisions" near the top of the screen.

The Notes of Decisions list cases relevant for interpreting or construing the statute, regulation, or court rule, arranged by topic. You can scroll through the list of topics in the left-hand sidebar, as well as filter the cases displayed by date, jurisdiction, and key number. Each case contains a one-sentence description or summary to demonstrate why the case is relevant for that topic. You may see some of the same cases filed under different topics throughout the Notes of Decisions. 

In the annotated version of a statute, regulation, or court rule, Citing References (Westlaw) contain all cases that cite to that statute, regulation, or court rule. If you have identified a relevant case, you should also check Citing References to see what subsequent cases have been cited to that case. The number of cases in Citing References may be voluminous, so take advantage of the filtering options (e.g., by jurisdiction, date, etc.) and also conduct searches within the results. 

You should use citing references during various stages of the research process:

• When looking for secondary sources discussing a particular primary source
• When working from a statute, regulation, or court rule to find cases
• When working from a relevant case to find other cases
• When checking to see whether cases are still good law

Citing References collect all cases that cite a particular statute, regulation, and court rule on Westlaw. Beyond cases, citing references also include other types of materials, such as secondary sources, administrative decisions, and court documents. 

After you have found the relevant statute, regulation, or court rule, click on the "Citing References" tab near the top of the screen.

Citing References include content beyond just cases, such as secondary sources and court filings. Make sure "Cases" is selected if you are only interested in finding cases that cite this statute, regulation, or court rule. 

You can narrow down the number of citing references by using the left sidebar to filter by jurisdiction (e.g., select a particular court or a level of court), restrict by a date or date range, and select whether the cases only include reported cases. 

To further narrow down your search, you can also conduct keyword searches within this set of results by using the "Search within results" option. Note that you can conduct searches using terms and connectors and Boolean operators (e.g., AND, OR, /s, etc.). 

This example used a statute, but note that Citing References are also available for cases so you can see what cases have cited to a particular case. You will need to check the Citing References for a case when confirming that it is still good law. 

Headnotes are summaries of a point of law that appear at the beginning of a case. Headnotes are written by editors at Westlaw and Lexis (sometimes the language is verbatim from the text of the opinion).

Headnotes are excellent research tools to assist you in finding other cases that address similar legal issues but do not cite headnotes in your work product. When citing a case, you should only cite to the actual text of the opinion written by the judge or justice. 

While reading through an opinion on Westlaw, you may encounter hyperlinks with numbers embedded throughout the text.

If you click on one of those links, you can view the corresponding West Headnotes summarizing that point of law.

Cases That Cite This Headnote: To find other cases that cite a particular headnote - that is, other cases that cite this case for this point of law - click on the "Cases that cite this headnote" link located below the one-sentence summary of the point of law.

Cases that cite a headnote consist of the citing references that specifically address that particular point of law in the case. Because cases usually address many issues, this can be a useful way to pinpoint the most relevant cases for your legal issue. 

West Key Number System: To view other cases from within or across jurisdictions addressing similar issues, use the West Key Number System in the right column that corresponds with the headnote of interest by clicking on one of those key number hyperlinks.

Whereas Citing References identify all cases that cite to a particular case (looking forward in time at the subsequent cases), the Table of Authorities identifies all of the cases relied upon and cited by a particular case (looking backward in time).

Although you generally would like to cite the most recent cases as possible, the leading case on a particular legal issue may be an older case, perhaps from a higher court. The Table of Authorities collects all of the citations within a case and describes the depth of treatment and how those cases were treated by this case. This makes it easy for you to verify the validity of authority that is being relied upon by a case.

To view the Table of Authorities for a case on Westlaw, click on the tab for "Table of Authorities."

The Table of Authorities provides a list of the cases cited in your case. The KeyCite flags offer clues as to whether your case is relying on other cases that may not be good law, which could be useful if you want to distinguish your situation from the case. 

To determine whether a case is still good law, you need to check the subsequent history of the case as well as subsequent citations to see how other cases have treated your case by using citators (KeyCiting on Westlaw). 

• Subsequent History: Subsequent history indicates whether your case was appealed and later overturned, or affirmed. 
• Subsequent Citations (Case Treatment): Subsequent citations indicate how other cases that came after your case have treated your case. 

The symbols and signifier phrases in citators (e.g., yellow flag, red stop sign symbol) only offer clues to how subsequent cases have treated your case, but you must actually read the cases of concern to see how or whether these subsequent cases have called your case into question, whether they apply your case, whether they distinguish your case, etc. The editors of Westlaw may not come to the same conclusion about how to "code" a case. Red flags or stop signs do not necessarily mean that a case is bad law. For instance, the case might be bad law on a different issue, the case itself might have been overturned, or the case may simply be unpublished (in some jurisdictions, court rules indicate that you cannot cite unpublished opinions). 

To view the subsequent history of a case, click on the "History" tab. Westlaw provides a map that depicts prior and subsequent history as well as a list of the direct history.

Subsequent Citations (Case Treatment):

To view the subsequent citations to a case, click on the "Citing References" tab. 

Citing References include all cases that cite to this case. Citing References also include other materials such as secondary sources and court documents, but to ensure that a case is still good law, you only need to check the cases. You can filter the citing references in the left sidebar to narrow the results to include only cases decided by courts that are binding on your court. 

• Treatment: This column indicates how the subsequent cases have treated the cited case (i.e., the case that you KeyCited). If the treatment is negative, this column will include a "Negative" notation.
• Depth: This column indicates the extent to which the subsequent cases have treated the cited case: examined (4 bars), discussed (3 bars), cited (2 bars), and mentioned (1 bar).
• Headnotes: This column indicates which headnotes in the cited case (i.e., the case that you KeyCited) contain the points of law discussed by the citing cases. 

Negative Treatment: 

Westlaw also offers a "Negative Treatment" tab containing negative direct history and negative citing references. Clicking on the status flag next to the case name will also bring you to this Negative Treatment report. 

The West Key Number System is a classification system of U.S. law that indexes cases into over 400 topics and more than 98,000 legal issues. Westlaw assigns a topic and key number to each legal issue within a case. The West Key Number System allows you to efficiently find other cases addressing your legal issue in any jurisdiction because all federal and state cases included in the system are organized using the same topics and by the same points of law.

Using the West Key Number System is particularly useful when you have identified a relevant case and would like to find additional cases addressing a certain point of law or legal issue from other jurisdictions.

A key number consists of a topic number, followed by a number to identify the issue within that topic. For instance, 349k28 is referring to the topic of Searches and Seizures (349) and the issue of abandoned, surrendered, or disclaimed items (k28). The image below shows this topic's place in the Key Number System's hierarchy: the topic of Searches and Seizures contains the subtopic In General, which contains the subtopic Persons, Places, and Things Protected, which includes - among others - the subtopic of abandoned, surrendered, or disclaimed items.

Please note that this strategy is only for conducting case law research on Westlaw. Lexis does not have a similar, comprehensive digest system, though it has started to develop a Legal Topics system.

• Stanford Law School: Searching with Topic and Key Numbers

  A quick reference guide from Westlaw on using the Key Number System

• Using the West Key Number System

  Another brief guide from Westlaw on using the Key Number System