The main purpose of this study is to ascertain the meaning, raison d' etre, extent and scope of the power of congressional inquiry on the bases of legislative and judicial precedents which may serve as guideposts in determining the proper conduct of congressional hearings. The researcher used the descriptive documentary analysis method, reviewing conceptual and related literature to trace the origin and development of the power of congressional inquiry, analyzing legislative and judicial precedents and other information from published congressional hearings and committee reports.