An interesting write up by Vincent Law and Raymond Chan of Mayer Brown on the recent Hong Kong case: K&L Gates v. Navin Kumar Aggarwal and Others  HKCFI 702.
This relates to a long standing case and I will not go into the details as the article itself does that very well. What is interesting in this judgement is the way the court dismissed a discovery application on behalf of the plaintiffs stating that is was a "a classic case of a fishing expedition" and that some of the document requests were "formulated too wide."
There is an on-going trend around the world, where common law prevails, to attempt to keep the costs of discovery/disclosure under control and to ensure that they are proportionate to the matter in dispute. One example of this is the new UK Practice Direction (Practice Direction 51U) which reforms various aspects of the document disclosure process in the Business and Property Courts of England and Wales. Amongst other things it introduces five models for extended disclosure, including a wide search-based disclosure model which follows a traditional train of enquiry approach. However, the main driver is to deliver reliable, efficient and cost effective solutions.
Although every case is different and there are cases when a train of enquiry approach will be appropriate and proportionate, it will certainly be far from the norm. This is summed up nicely in the article and applies to many jurisdictions - "The Decision serves as a reminder that requests for documents in an application for specific discovery must be drafted properly and limited to documents which are relevant to the contested issues."
the Court affirmed and applied the well-established legal principles on applications for discovery which provide, where the application relates to a class of documents, the class should not be defined or described too widely and should not be defined in a way which includes documents which are irrelevant. The class of documents must also be classified by their nature, rather than described as documents going to a particular issue.