Law librarians teach law students and new lawyers that state and federal appellate court briefs are treasure troves, but they are not the easiest documents to search.
For example, in Oregon, unless you have a subscription to Lexis or Westlaw, and can afford to buy into their briefs databank, and need to search only relatively recent briefs, you have to resort to needle-in-a-haystack types of research. (A law librarian can recommend some research tips, but the research still takes time.)
Web-based, publicly-accessible, moderately priced, and searchable digital briefs banks rise and fall, but that’s a good thing. One needs to experiment a lot to find the right online business model and database. To read about a recent effort: