This chapter discusses the various forms of processing that are being advocated for geographic information systems and distributed data sets in multicriteria decision making (MCDM) problems. Case-based Reasoning avoids the difficulty of knowledge elicitation by dispensing with the need to formalize and structure knowledge into rules. The importance of expert knowledge in MCDM rests on the premise that determining which variables must be considered, how they vary spatially, and how this knowledge is to be used in making decisions is the role of a few highly trained individuals. In 1994 at the Gwich’in Renewable Resources Workshop, the Gwich’in identified the need to use traditional knowledge to meet the objectives of their 1992 Comprehensive Land Claim Agreement. The search tools are related intimately to the knowledge acquisition process because the user searches the case base which resulted from the authoring or knowledge acquisition process.