This report will provide an overview of some of the more common legal, procedural and practical issues, questions, and problems that committees have faced in the course of an investigation. Following a summary of the case law developing the scope and limitations of the power of inquiry, the essential tools of investigative oversight--subpoenas, staff interviews and depositions, grants of immunity, and the contempt power -- are described. Next, some of the special problems of investigating the executive are detailed, with particular emphasis on claims of presidential executive privilege, the problems raised by attempts to access information with respect to open or closed civil or criminal investigative matters, or to obtain information that is part of the agency deliberative process, and the effect on congressional access of statutory prohibitions on public disclosure. The discussion then focuses on various procedural and legal requirements that accompany the preparation for, and conduct of, an investigative hearing, including matters concerning jurisdiction, particular rules and requirements for the conduct of such proceedings, and the nature, applicability and scope of certain constitutional and common law testimonial privileges that may be claimed by witnesses. The case law and practice respecting the rights of minority party members during the investigative process is also reviewed. The report concludes with a description of the roles played by the offices of House General Counsel and Senate Legal Counsel in such investigations.