The prosecutorial practices surveyed were use of grand jury subpoenas and Internal Revenue Service summonses to defense attorneys to secure information on clients, forfeiture of defense legal fees, use of undercover informants as 'clients,' and actions to disqualify defense attorneys. Sixty-six percent of respondents reported experiencing one or more of these practices within the last 30 months (1983 to mid-1985). Respondents reporting the most frequent instances of these practices were affluent, experienced private attorneys who handle white-collar and drug cases. A total of 731 attorneys changed some practice activities as a result of these not taking cases they would have formerly taken, keeping fewer records, or keeping more detailed records. Results suggest courts should carefully scrutinize prosecutorial practices vis-a-vis defense attorneys to ensure they do not undermine the adversarial process and violate defendants' right to counsel. Further, Congress should modify current legislation or adopt new measures to prevent prosecutors' interference with proper defense practices. 10 tables and the questionnaire.