At the firm I'm at, we've spent a lot of time and effort developing systems, such as Matter Pages, our document management system, and more, that take advantage of the ubiquitous "matter number." This is simply a six-digit unique identifier that originates in the billing system but that usually provides an excellent way to organize and find all kinds of information a particular case team uses and needs.
As I'm sure others have noted, however, the matter-number system can break down. It probably functions quite well for at least 85-90% of large firm engagements.
Matter numbers can be too specific for litigation purposes when multiple matters (most often torts) are consolidated in a federal Multi-District Litigation (MDL) or a state equivalent, or when the client requests that separate matters be opened to handle discovery and then trial or pretrial matters.
Matter numbers can be too general from a litigation KM perspective when a client asks that all of its cases be lumped into one overburdened matter number, or when one matter has a number of cases for other reasons, such as, insurance coverage.
In either case, the real "project" that a case team is engaged in cannot readily be tracked. Neither events, now witnesses, nor sets of dispositions that might occur with a group settlement can be effectively followed through the matter numbers. The same problem arises with matters that may partially have some information segregated by matter but that may have very significant common elements with another set of matters, such as expert witnesses who testify in a set of cases united by scientific or occupational facts.
I've recently been working on a system, still in development, that solves many of the problems of overly general and overly specific matter numbers. It's based on Sharepoint 2007 lists, with separate lists for cases, witnesses, attorneys & staff, calendar events, and so forth. The basic idea is to create a way to track and aggregate information about the individual cases and to leverage the existing systems, such as matter pages and pleadings binder systems, that we can link to through the intranet. Each item in one list contains links to the related items on the other lists, so that you can go from a view of a deposition to a view of the assigned attorney or to a view of the information we have about the matter.
Two features of Sharepoint 2007 make this approach more palatable than it would have been in Sharepoint 2003. One is that you can subscribe to changes in a list. That has the tremendous advantage of letting someone keep track of all changes to a project, regardless of how many different people are entering information. Currently subscriptions have to be by email, unfortunately, but they could also be routed through RSS with implementation of enterprise RSS.
The other significant improvement might seem trivial but it has big implications. In 2003 you had to choose whether to put text or a hyperlink into a given field; you couldn't intermingle the two. In 2007 there is an option (though curiously not the default option) to have a field with many lines of rich text including links. This made possible the feature in my case management system where a witnesses' list item has room for links to multiple deposition or testimony transcripts, and much more.
Working on this project has highlighted some room for improvement in our existing matter pages system, particularly in its inability to handle the relationship between an event such as a deposition or pretrial hearing, a matter, the assigned attorney and the other staff working on the event, and any witnesses who may be involved. But the case team involved is excited about the system so far so I hope it will prove valuable for them.