Final answer:
KeyCite is the Westlaw research service feature used to determine if a case, law, or regulation remains authoritative. Accurate legal research requires precise keywords and the assistance of librarians can be very helpful in this process.
Step-by-step explanation:
The Westlaw research service feature that is utilized to ascertain whether a case, law, or regulation remains good law is known as KeyCite. This tool is crucial for legal research and ensures that legal professionals and students are referencing current and authoritative legal materials. When conducting legal research, whether through a college library website with access to databases or using search engines it is important to use precise keywords to find relevant and focused results. Librarians are also a valuable resource for assisting in this process. While KeySearch might refer to a searching method within Westlaw, and WestlawNext and Campus Research are other services by Westlaw, KeyCite specifically is the citation checker tool employed to verify the validity and citability of legal documents.