The study (1) defined the user community, (2) performed an onsite survey of representative users, (3) developed an analysis methodology and performed requirements analyses, and (4) prepared a statement of system requirements. The user community was defined to include law enforcement, courts, corrections, prosecution, and probation and parole. Each function was classified as local/regional, State, and Federal. Preliminary results of analyses for 1983 cover estimates of message volume in millions, average character length per message type, and average traffic load expressed in bits per second for State-to-State and State-to-national communications. Current types of traffic projected to 1983 are expected to constitute about 18.9 percent of the traffic load, with new applications accounting for 81.1 percent of the traffic, which represents a major increase in services supplied by a Nalecom-type system. Use of current types of services will increase by a factor of 15 for State-to-State traffic, and State-to-national traffic will increase by a factor of 4.8 over 1972 levels. Transmission of fingerprint data is expected by 1983, and all States are expected to develop driver and vehicle records; through a State identification bureau, an officer will be able to access any other such bureau over Nalecom. Criminal justice planners, administrators, and managers are expected to use the national data banks containing information on offender transaction statistics, Federally sponsored research programs, and the results of innovative law enforcement techniques. A national criminal information system and the preliminary transmission of laboratory specimen facsimiles are also anticipated. Tabular data are provided. (Author summary modified)