GAO reviewed 157 cases studied by 7 Federal district courts and the D.C. Superior Court and 83 local studies ordered by district courts during fiscal 1981. It found that the Judicial Conference and the Federal Prison System have not established criteria for the selection of appropriate cases for observation and study. They have failed to develop and disseminate guidance on the types of questions that experts can be expected to answer. Finally, they have failed to establish a system to evaluate whether the studies have met the needs of the district courts. Despite urgings from the Judicial Conference and the Federal Prison System that study objectives and referral questions be included in cases committed for study, this was not done in 76 of the 157 cases. Further, 78 percent of all studies ordered in fiscal 1981 were the more costly and lengthier Federal studies rather than local studies. On the basis of these findings, GAO recommends that criteria for the selection of cases appropriate for study be developed. Guidance on the questions clinical experts can be expected to answer also should be developed and disseminated to district courts. Finally, a system of regular evaluation of the utility of such studies is needed. A series of letters commenting on this report is appended.