Fed. R. Civ. P. 26(b)(3) and its state counterparts protect from discovery "documents and tangible things that are prepared in anticipation of litigation." This obviously includes civil litigation. But what about other forms of adversarial dispute resolution?
In Ellingson v. Piercy, Case No. 2:14-cv-04316-NKL, 2016 U.S. Dist. LEXIS 78803, at *12 (W.D. Mo. June 16, 2016), the court held that the work product doctrine extended to emails related to a "coroner's inquest [which] was a quasi-judicial proceeding." Other courts have extended work product protection to documents motivated by adversarial regulatory proceedings, arbitrations (rather than mediations), and other public and private processes analogous to side-versus-side litigation.
Of course, the attorney-client privilege protection can protect communications in any setting, regardless of litigation or anticipated litigation. As in so many other ways, the work product doctrine involves more subtle and varied issues than the attorney-client privilege.