Work-Product Rule vs. Attorney-Client Privilege (Legal Ethics)
The work-product doctrine is more inclusive than attorney–client privilege. Unlike the attorney–client privilege, which includes only communications between an attorney and the client, work-product includes materials prepared by persons other than the attorney him/her self: The materials may have been prepared by anybody as long as they were prepared with an eye towards the realistic possibility of impending litigation. Additionally, it includes materials collected for the attorney such as interrogatories, signed statements, other information acquired for the prosecution or defense of a case.
However, "memoranda, briefs, communications ... other writings prepared by counsel for his/her own use in prosecuting the client's case ... mental impressions, conclusions, opinions, or legal theories" are never discoverable by an opposing party. However, the work-product doctrine is also less powerful than the attorney–client privilege, and therefore may be overcome by a showing of necessity. (https://en.wikipedia.org/wiki/Work-product_doctrine#Comparison_with_attorney.E2.80.93client_privilege)
However, "memoranda, briefs, communications ... other writings prepared by counsel for his/her own use in prosecuting the client's case ... mental impressions, conclusions, opinions, or legal theories" are never discoverable by an opposing party. However, the work-product doctrine is also less powerful than the attorney–client privilege, and therefore may be overcome by a showing of necessity. (https://en.wikipedia.org/wiki/Work-product_doctrine#Comparison_with_attorney.E2.80.93client_privilege)