To determine how this service affects Federal policy to encourage State and local laboratory independence, GAO reviewed randomly selected requests for analyses at the laboratories of the FBI, the DEA, and the BATF. Officials at 15 State and local crime laboratories were also interviewed about their operations. Results show that all three Federal laboratories provide many free services to State and local requestors; percentages of laboratory workload devoted to these requests were 9 percent at the DEA and BATF and 25 to 79 percent at the FBI. State and local law enforcement agencies, which can bypass their own laboratories and submit evidence directly to Federal laboratories use the Federal Laboratories for services ranging from routine procedures to complex analyses they feel their own laborabories cannot perform. Moreover, the Federal labs generally perform any analyses requested of them, despite the fact that the majority are within the capabilities of local laboratories. These practices contradict a Federal policy promoting local laboratory independence that has heavily financed local laboratory development over the past 10 years. Moreover, budget cuts will soon curtail many such Federal laboratory servces. Therefore, the following activities are recommended to Federal agencies as a plan to help State and local agencies prepare for greater independence: (1) provide a time schedule for phasing out services, (2) discontinue accepting routine requests, and (3) define the complex analyses that the Federal laboratories should continue to perform. Footnotes, tables and an appendix presenting the numbers of State and local requests received by the FBI during 1978-79 are given. (Author abstract modified)