On expelling members of Congress
What does Congress do when one of its members is convicted of crime, or strays into the mire of treason? It can expel them. The process is rarely used, and this report from the Congressional Research Service about expelling congressmen for illegal acts makes for interesting history about the group Mark Twain dubbed our "native criminal class."
Twenty members have been expelled during our history, most of them prior to the Civil War. The last expulsion was in 2002. Under what circumstances a member can be expelled are somewhat vague. For example, regarding questionable conduct before a member is elected:
...the text of the Expulsion Clause, its history, and subsequent historical practice all support a broad, but not unlimited, power in both the House and Senate to expel Members for conduct occurring during a Member’s term of office. However, whether the House and Senate have authority to expel a Member for conduct that solely occurred prior to an intervening election appears to be unresolved. House and Senate practice (drawn primarily from committee reports relating to expulsion resolutions that were either not approved or not acted upon by the full body) concerning expulsions for prior misconduct are relatively inconsistent and do not appear to establish a clear and constant interpretation of whether prior conduct (i.e., conduct occurring before an intervening election) may form the basis for an expulsion. While the reasoning underlying the House and Senate approach to expulsions for prior misconduct does not appear to be uniform, and thus may have limited value in discerning the meaning of the constitutional power, there is some evidence to suggest that both the House and the Senate have, on occasion, “distrusted their power” to expel for such conduct.
It appears Congress is willing to leave it up to voters to judge such matters (all the more reason to know your candidates and their backgrounds as much as possible). What about those who have been expelled?
In early 1861, the Senate considered the status of Members representing states that were contemplating secession, ultimately expelling 10 Members in a single vote after the war had begun. In those cases, the Members represented southern states that had seceded from the Union, and the Members had not formally resigned from the Senate. The expulsion resolution cited the Members’ failure to appear in the Senate and alleged that the Members “are engaged in said conspiracy for the destruction of the Union and Government, or, with full knowledge of such conspiracy, have failed to advise the Government of its progress or aid in its suppression.” Other examples of Civil War expulsions involved Members who represented states that had not seceded, but who themselves had supported secessionists.
For more than a century following the Civil War expulsions, neither the House nor the Senate expelled a Member. The two most recent expulsions—both Members of the House—concerned a broader range of behavior, beyond disloyalty to the country, for which Congress would expel one of its Members. Those expulsions resulted after the Representatives were convicted of criminal charges under various public corruption statutes. In 1980, a Member was expelled following a criminal conviction on charges relating to receiving a payment in return for promising to use official influence on legislation in the so-called ABSCAM investigation. The most recent expulsion occurred in 2002, when the House expelled a Member who had been convicted of various criminal charges relating to his official actions in Congress, including bribery, illegal gratuities, obstruction of justice, defrauding the government, filing false tax returns, and racketeering.
It should be noted that in a number of cases, Members’ behavior has drawn public calls for expulsion or preliminary proceedings by the respective house toward potential expulsion, but ultimately resulted in the Member resigning prior to a formal decision to expel.
The threat of expulsion is enough to get some corrupt members to resign and avoid further disgrace (if that's possible). The report is fascinating for its history -- discussing the roots of the expulsion power, how the Framers debated it, and how Congress has employed it.
Useful information for the future -- should it be necessary.