In what case was the principle of specifying documents in a subpoena established?

The principle of specifying documents in a subpoena was established in the case of Commissioner of Railways v Small. This case clarified the requirements for a subpoena to be valid and enforceable, particularly emphasizing that a subpoena must clearly describe the documents that are sought. The Court highlighted that ambiguity in the description of documents can lead to difficulties in compliance and can potentially render the subpoena ineffective. This principle is crucial within the context of civil procedure, ensuring that parties to a legal action can adequately prepare their cases with the relevant material, while also protecting the rights of individuals or entities from overly broad or vague requests for documentation. By mandating specificity, this case underscores the importance of clarity in legal requests, facilitating a more efficient judicial process.