I practice in Australia. I can see a lot of use in people doing a course on defence before getting a CCW permit.
I think there is limited scope for an 'expert' in respect to civilian court matters.
The only caveat I would add to that is when one is using a good attorney (perhaps a QC with particular skills you want) and he has limited experience with firearms. A few sessions with an 'expert' could provide him with a necessary education.