The DA must follow this rule: http://codes.findlaw.com/ca/penal-code/pen-sect-1054-1.html.
The DA also has obligations under Brady v. Maryland: https://scholar.google.com/scholar_case?case=955043312626967...
The defense must follow this rule: http://codes.findlaw.com/ca/penal-code/pen-sect-1054-3.html