Recording search histories, presenting them to the searcher, and building additional interface tools on them offer many opportunities for supporting user tasks in information seeking and use. This study investigated the use of search history information in legal information seeking. Qualitative methods were used to explore how attorneys and law librarians used their memory and external memory aids while searching for information and in transferring to information use. Based on the findings, interface design recommendations were made for information systems. Results of the study from the legal user group presented evidence of the usefulness of search histories and history-based interface tools. Both user manifestations and researcher observations revealed that searchers need historical information in information seeking. Search histories were found to be useful in many user tasks: memory support, search system use, information seeking, information use, task management, task integration, and collaboration. Integrating information across various user tasks and collaborating with others are extensions of traditional information-seeking and use models. These findings encouraged the design of user interface tools and guidelines building on search history information. (English)