In The Case Against Lame Duck Impeachment, Yale Law Professor Bruce Ackerman argues that the bill of impeachment against President Clinton, passed in December 1998, expired on January 3rd 1999, when a new House of Representatives began its term in office.
It is unconstitutional for the Senate to begin a trial unless a majority of the newly elected House once again charges the President with "high crimes and misdemeanors."
The newly elected House of 1999 contains 40 new members and five more Democrats, suggesting that a new House vote could produce a different outcome on one or both of the lame duck articles of impeachment. Given this fact, the Chief Justice has a constitutional responsibility to dismiss the lame duck bill of impeachment and call a halt to the Senate trial unless and until the newly elected House votes a new bill of impeachment.
Professor Ackerman supports this conclusion with an analysis of all applicable precedents, ranging from early English history through the Founding period through the enactment of the 20th amendment to the Constitution in 1933. He shows that the Framers of the 20th amendment made a systematic effort to control the abuse of lame duck authority, and that they would have been appalled by the House's rush to impeach a sitting president.