"The Senate has, from the 1st Congress (1789-1790), valued the importance of decorum in debate and included a 'call to order' mechanism in its rules to sanction Senators who use 'disorderly' language. The rules adopted in 1789 contained such a call-to-order provision, and its language has been amended multiple times over the years. Table 1 of this report details the historical evolution of the rule. The present form of the Senate's call-to-order provision was adopted on June 14, 1962. Senate Rule XIX identifies specific language that is considered disorderly. This includes language directly or indirectly imputing to another Senator or Senators 'any conduct or motive unworthy or unbecoming a Senator' (paragraph 2) and referring 'offensively to any State of the Union' (paragraph 3). Rule XIX prohibits imputing conduct or motive 'by any form of words' to a sitting Senator, which includes not just original words spoken in debate but quotes, news articles, and other materials. The statements in paragraphs 2 and 3 are not considered to be a comprehensive recitation of language that may violate decorum in Senate debate. Although precedents on the subject are mixed, Senators have at times also been called to order for making disparaging references in debate to the House of Representatives or its Members."
CRS Report for Congress, R45241