Court registries generally destroy files after 15 years, however some material (primarily court orders) is sent to the provincial archives. There are exceptions, so some of the court files sent to the archives will contain more kinds of documents than others.
To find out if the archives has a particular document, contact BC Archives and give them as much information as you can. They will be able to tell you if they are likely to have the material and what will be required to obtain it.
An individual may go to the archives in person, however not all court documents are available to the public. If there is anything on a reel of microfilm or in a box of documents that is restricted, the entire reel or box is off limits - which means that members of the public would not be able to search for documents there themselves.