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Westlaw New Zealand - How to find cases on a point of law using the Key Number System

Last Published: May 28, 2020

The West Key Number System identifies and indexes legal concepts so you can find cases stating or applying a legal concept. 

Experienced legal editors have read, summarised and classified case law by topic and subtopics that represent specific points of law. Each specific point of law is assigned a unique number, called a Key Number.

Browse the West Key Number System

  1. Access the West Key Number System by clicking Key Numbers on the homepage.
  1. Select a key number to browse and locate cases on a relevant topic, e.g., 24 Employment Law.
  1. A list of sub-topics and their key numbers will be displayed.

Click a key number to view relevant cases on that topic, e.g., Employment>Discrimination > Age

  1. Click the case title to view the judgment.


Search the West Key Number System

Use the title search bar to search for classifications relevant to your issue.

  1. Enter your search term into the Title Search bar and click Search, e.g., discrimination.
  1. A list of the relevant topics and key numbers will be displayed.

Select the tick boxes next to the key numbers relevant to your research issue.

Click View Cases.

  1. The cases relevant to the selected key numbers will be displayed.

To narrow your results, you can filter by key number, jurisdiction, or date.

Use the plus (+) symbols to expand and select the required jurisdiction.

Select from the last 6 months, 12 months, 3 years, or enter a specific date or date range.


You can use the Key Number System to find cases discussing similar legal concepts and principles.

  1. Specific points of law addressed in a particular case will be listed in Classifcations on the document tab of a case. 
  2. You can change the presentation of the classification using the view options at the top right of the first Key Number.
  1. Scroll down the page to select a key number to  locate cases on a relevant topic, e.g., 24k228 Failure to comply with health and safety duty exposing a person to risk of death or serious injury
  1. The results outline that there are 94 cases that are classified as offence cases under employment law and of those cases, 76 are classified as Failure to comply with health and safety duty exposing a person to risk of death or serious injury
  1.  Filters to narrow your search are available in the left pane. 

Enhanced Key Number Searching:


Finding cases using the Key Number system provides results that display the first few sentences of the cases.  There are not many filters so if you have a large result you may want to try this method instead:


  1. From the New WL home page, click the Key Number System box.
  2. Find Title Search on the right side of the page and enter a topic e.g., damages – search.
  3. In the result list, choose the damages title that is applicable to you – e.g., the damages title under the main heading of Contract.
  4. You can see that there are two further sub-topics, supposing you want cases about quantum.  On the page you are looking at, the relevant key numbers are below – make a note of these numbers:

              18 (this is the overall Key Number for Contract)

              K (this just stands for Key Number)

              9 (this is the key number for Quantum)

  1. Return to the New WL home page, click on Cases, then Advanced Search near the top right of the screen.
  2. Into the Key Number/Classification field enter 18K9
  3. You will get results for the cases that match that topic, as well as more filters, including one that enables you to run a search within the existing results.

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