Congress's contempt power is the means by which Congress responds to certain acts that in its view obstruct the legislative process. Contempt may be used either to coerce compliance, to punish the contemnor, and/or to remove the obstruction. Although arguably any action that directly obstructs the effort of Congress to exercise its constitutional powers may constitute a contempt, in recent times the contempt power has most often been employed in response to non-compliance with a duly issued congressional subpoena – whether in the form of a refusal to appear before a committee for purposes of providing testimony, or a refusal to produce required documents. This book examines the source of the contempt power, reviews the historical development of the early case law, outlines the statutory and common law basis for Congress's contempt power, and analyses the procedures associated with inherent contempt, criminal contempt, and the civil enforcement of subpoenas.