For the police survey, every officer in one busy and one quieter subdivision of five departments completed an interview form for every crime suspect interviewed over a 6-week period. To obtain information on court time spent on cross-examination of police evidence, surveys were conducted of all contested cases in nine Crown Court centers and five magistrates' courts for 3 months of summer 1979. The tape recording experiment showed that acoustic conditions of police interviewing rooms would need upgrading for recordings to be reasonably intelligible. While cassette recorders would be easiest to operate, ones that meet the needs of police interrogation are not generally available and would have to be specially produced. Complex security precautions are not necessary, but an electronic tamper-proof device could be developed to meet any requirements. If police make full transcriptions of all tape recordings, the costs approach 15 million English pounds per year for implementation. However, reducing or eliminating requirements for written transcriptions would lower the cost to 1.6 or .5 million English pounds. U.S. police departments restrict tape recording interrogations to the most serious offenses, typically homicide, rape, and robbery. The system cost of such a policy in England would be .42 million English pounds annually if recordings were made at the subdivisional levels and less using centralized facilities. Tables, 10 references, and detailed descriptions of the surveys and cost model are provided.