The first task of the lawyer is to identify the legal problem in the client's situation. When the lawyer has described the problem as a set of facts, the search begins for the legal norms which govern the problem. Legal sources relevant to the problem are obtained. In a simplified model of the legal decisionmaking process, some factors contributing to uncertainty may be identified. First, in the process of refining the problem into a set of facts, lawyers may disagree upon what facts are relevant and the degree to which they must be supported by proof. Second, because lawyers have access to individually constructed information systems, different sources may be obtained. Third, in the process of constructing relevant legal norms, differences may be disclosed as to what sources actually are relevant, what arguments may be derived from these sources, and what weight these arguments carry. Errors may also be caused by malfunctions of information systems. The paper suggests that an improved information system would reduce uncertainty in two respects: it would even out the differences in availability between different lawyers and improve retrieval tools and it would make retrieval of relevant sources more efficient. Three figures, 3 footnotes, and 19 references are included.