Zotero provides a Case item type, but it does not tend to recognize this format from your browser.
Instead, you can save it as a Webpage, but you will still need to manually edit most of the item information in Zotero (see below). However, Zotero will save the URL and a snapshot of the webpage, so this may still be a helpful step for you in documenting your research.
Once you have a case saved as an item (or have manually started a new item), change the Item Type to Case. You can then fill in the remainder of the fields.
Note: Some formats of Canadian citations are not interpreted correctly by Zotero when added to a document. For example, if your reporter citation includes a series number (e.g. 35 OR (2d) 423), it is easier to add the entire citation in the "Reporter" field, because Zotero does not have a specific field for the 2d series number.
Check out Zotero's Support page for more tips and tutorials.
York University Library's Zotero guide has additional information that is not discipline-specific.