Formulated in the 1960s by lawyer and planning scholar Paul Davidoff, the advocacy planning model takes the perspective that there are large inequalities in the political system and in the bargaining process between groups that result in large numbers of people unorganized and unrepresented in the process. It concerns itself with ensuring that all people are equally represented in the planning process by advocating for the interests of the underprivileged and seeking social change.[16][17] Again, public participation is a central tenet of this model. A plurality of public interests is assumed, and the role of planner is essentially the one as a facilitator who either advocates directly for underrepresented groups directly or encourages them to become part of the process.[10]