4.13. Common Purpose (Roles and Responsibilities).The importance of sound appraisals in federal acquisitions cannot be overstated. It is the United States’ obligation to serve the general public and protect the common welfare by paying just compensation whenever property is needed for public purposes, and reliable, objective valuations are critical to achieving this end.1187 Appraisers, landowners, attorneys, and government agency staff all play important roles in the federal acquisition process, whether or not litigation is anticipated.