The Speech or Debate Clause (Clause) of the U.S. Constitution states that "[F]or any Speech or Debate in either House," Members of Congress (Members) "shall not be questioned in any other Place." The Clause serves various purposes: principally to protect the independence and integrity of the legislative branch by protecting against executive or judicial intrusions into the protected legislative sphere, but also to bar judicial or executive processes that may constitute a "distraction" or "disruption" to a Member's representative or legislative role. Despite the literal text, protected acts under the Clause extend beyond "speeches" or "debates" undertaken by Members of Congress, and have also been interpreted to include all "legislative acts" undertaken by Members or their aides. Judicial interpretations of the Clause have developed along several strains. First and foremost, the Clause has been interpreted as providing Members with general criminal and civil immunity for all "legislative acts" taken in the course of their official responsibilities. This immunity principle protects Members from "intimidation by the executive" or a "hostile judiciary" by prohibiting both the executive and judicial powers from being used to improperly influence or harass legislators. Second, the Clause appears to provide complementary evidentiary and testimonial privileges. Although not explicitly articulated by the Supreme Court, lower federal courts have generally viewed these component privileges as a means of effectuating the purposes of the Clause by barring evidence of protected legislative acts from being used against a Member, and protecting a Member from compelled questioning about such acts. The testimonial privilege component of the Clause has given rise to significant disagreement in the lower courts. The U.S. Court of Appeals for the District of Columbia Circuit (D.C. Circuit) has held that the Clause's testimonial privilege encompasses a general documentary nondisclosure privilege that applies regardless of the purposes for which disclosure is sought. To the contrary, the U.S. Court of Appeals for the Third Circuit and the U.S. Court of Appeals for the Ninth Circuit have rejected that position, holding instead that, at least in criminal cases, the Clause prohibits only the evidentiary use of privileged documents, not their mere disclosure to the government for review as part of an investigation. [ABSTRACT FROM AUTHOR]