We have a collection development policy that guides most of our decisions along certain lines, including subject area. We do have the latitude to acquire things on request for addition into the collection provided that they would meet the long-term use of the collection along those subject lines. Where something perhaps doesn't meet those subject lines, we will bring the item in by interlibrary loan if we believe that the interest is of short-term use, or if it's an older publication that we just don't happen to have in our collection.
On May 3rd, 2018. See this statement in context.