Speech and Debate: No Immunity from Corruption or the Constitution
Arguments that the Speech or Debate Clause of the Constitution does not cover bribery often invoke existing caselaw that has found that it applies to activities directly involved in legislating (even speeches and press releases outside the halls of Congress), and since taking a bribe is not inherent in lawmaking that the FBI's raid on Mr. Jefferson's offices is not prohibited. Outside the Beltway makes this argument well.
However, I think this argument addresses the wrong question. It is off the mark to imply that some contend that bribery should not be investigated and prosecuted. The issue at hand is whether the raid itself interfered with an activity inherent in lawmaking, and I would argue that it did: privacy of the legislator's office. Members of Congress need assurance of confidentiality of the many sensitive materials that their work exposes them to--both personal communications in the daily business of politics, and information about national security or delicate foreign relations issues they handle. The Supreme Court has clearly considered Speech and Debate to include written documents, and that must include those held in congressional offices.
Subpoena, rather than search and seizure, should be the preferred method of obtaining evidence to investigate congressional corruption. Forcibly obtaining documents by midnight raid creates and atmosphere of siege, and will encourage congressional offices to take pre-emptive countermeasures that may make corruption investigations more difficult to undertake in the future.
The privledge of Speech and Debate, broadly conceived, stemmed from the English Bill of Rights as a response to Tudor monarchs' intimidation of members of parliament. Let us hope that we don't confuse the legitimacy of investigating corruption with the illegitimacy of violating a Constitutional clause and a principle of government that ensures that the bills passed by Congress are not just a rubber stamp for the will of the Executive.