Law school reading required copious and fastidious amounts of higher-level thinking skills; as such, time spent reading is not so much spent on reading as thinking.
I could "read" a case in ten minutes, by the most literal definition of the word, but it could very easily take three hours or more to delve into all of the intricacies associated with said case. This is why law students spend time in the library- not because they're working on phonics and reading speed.
I think that a speed-reading course would be a waste of time. If you find a speed-thinking course, however, let me know. That's the only course that will help in law school.