要有提告人, 有實質野告, 然後要告港鐵
https://hsfnotes.com/asiadisputes/2015/11/10/when-will-the-hong-kong-court-grant-pre-action-discovery/
The Court has the power to grant pre-action discovery to a person who appears likely to be a party in anticipated proceedings where the documents in question are (i) likely to be or have been in the possession, custody or power of the person against whom the order is sought; and (ii) 'directly relevant' to an issue arising or likely to arise in the anticipated proceedings.