The authority to expel a Member is expressly provided for in the Constitution at Article I, Section 5, clause 2. In the United States Senate, 15 Senators have been expelled, 14 during the Civil War period for disloyalty to the Union (one expulsion was later revoked by the Senate), and one Senator was expelled in 1797 for other disloyal conduct. In the House of Representatives, five Members have been expelled—3 during the Civil War period for disloyalty, one in 1980 after conviction of bribery and conspiracy in congressional office, and one Member in 2002 after his convictions for bribery, receipt of illegal gratuities, and other corruption charges, while several other Members, facing potential expulsion, resigned their offices prior to action by the full House of Representatives. Censure

The term "censure," unlike the term "expel," does not appear in the Constitution, although the authority is derived from the same clause in the Constitution at Article I, Section 5, clause 2, concerning the authority of each house of Congress to "punish its Members for disorderly Behaviour." The Standing Orders of the Senate provide that the Select Committee on Ethics may recommend to the Senate disciplinary action against a Member "including, but not limited to, in the case of a Member: censure, expulsion, or recommendation to the appropriate party conference regarding such Member's seniority or positions of responsibility ...."
A "censure" in the Senate has traditionally meant the "punishment" imposed by the Senate when the full body formally disapproves of conduct or behavior of a Member by way of the adoption, by majority vote, of a resolution expressing such condemnation or disapproval. The term "censure" is used to describe the formal action of the Senate adopting a resolution expressing the body's "censure," "condemnation," "denouncement," or general disapproval of a Member's conduct even when the word "censure" is not expressly included in the language of the resolution. Denounce

The term "denounce" has been used in two relatively recent censure resolutions in the Senate. Even when not a violation of a particular law or rule, the Senate has censured Members for conduct when found contrary to "acceptable norms of ethical conduct in the Senate," contrary to "good" or "accepted morals" and "senatorial ethics," when found to "derogate from the public trust expected of a Senator," and/or for "reprehensible" conduct which brings the Senate into "dishonor and disrepute." It should be noted that prior to 1968 there were no written Senate ethics rules. The Senate has "censured" Members for violating orders of secrecy of documents in their possession; for fighting in the Senate; for allowing a lobbyist with interests in particular legislation to be on one's staff and on a committee considering such legislation, with access to the secret meetings and considerations of the committee; for non-cooperation and abuse of investigating committees of the Senate; and for financial irregularities concerning contributions, official expenses, and outside income. Conclusion

Expulsions in the United States Senate, as well as in the House of Representatives, have been generally reserved for the most serious misconduct of a Member of Congress, historically concerning disloyalty to the government, or the conviction (or evidence) of an offense involving official corruption and/or the abuse of one's official position in Congress. The action of the full United States Senate formally adopting, by a vote requiring the majority of Members present and voting, a resolution disapproving of a Senator's conduct is considered by parliamentarians and historians as a "censure" of that Member.
The authority of the United States Senate (as well as of the House) to establish the rules for its own proceedings, to "punish" its Members for misconduct, and to expel a Member by a vote of two-thirds of Members present and voting, is provided in the Constitution at Article I, Section 5, clause 2. This express grant of authority for the Senate to expel a Senator is, on its face, unlimited—save for the requirement of a two-thirds majority. In the context of what the Supreme Court has characterized as, in effect, an "unbridled discretion" of the body, expulsions in the Senate, as well as the House, have historically been reserved for cases of the most serious misconduct: disloyalty to the government or abuses of one's official position. The Senate has actually expelled only 15 Members—14 of those during the Civil War period for disloyalty to the Union (one of these expulsions was subsequently revoked by the Senate), and the other Senator during the late 1700s for disloyal conduct. The House of Representatives has expelled only five Members in its history, three during the Civil War period, one in 1980, and another in 2002, after convictions for bribery and corruption offenses related to official congressional duties. In the Senate, as well as in the House, however, other Members for whom expulsion was recommended have resigned from office prior to official, formal action by the institution.
The term "censure," unlike the term "expel," does not appear in the Constitution, and has traditionally been used to describe the "punishment" imposed by the Senate under authority of Article I, Section 5, clause 2, when the full body formally disapproves of conduct by way of the adoption of a resolution expressing such condemnation or disapproval. There is no specific forfeiture of rights or privileges that automatically follows a "censure" by the Senate. The term "censure" is used to describe the action of the Senate formally adopting a resolution expressing the body's "censure," "condemnation," "denouncement," or other expression of disapproval of a Member's conduct, even when the word "censure" is not expressly included in the language of the resolution. There is no specific or official hierarchy or ranking of the terms that have been employed in a censure resolution, although there may be certain connotations associated with the language used in a resolution because of precedents and associations with past Members disciplined.
The Senate has censured nine Senators for various misconduct, including conduct not a violation of any law or specific written Senate ethics rule, when such conduct is found contrary to "acceptable norms of ethical conduct in the Senate," contrary to "accepted morals" and "senatorial ethics," when found to "derogate from the public trust expected of a Senator," and/or found to be "reprehensible" conduct which brings the Senate into "dishonor and disrepute." Conduct resulting in Senate "censure" has included violating orders of secrecy of documents; fighting in the Senate ("censure"); allowing a lobbyist with interests in particular legislation to be on official staff with access to the secret considerations of the legislation by committee ("condemn"); non-cooperation and abuse of investigating committees of the Senate ("condemn"); financial irregularities concerning political contributions ("censure"), office expenses and contributions ("denounce"), and excessive honoraria, official reimbursements and gifts ("denounce").