91. "Power of the Deputy Chairman or other person to perform the duties of the office of, or to act as, Chairman.-
(1) While the office of Chairman is vacant, or during any period when the Vice-President is acting as, or discharging the functions of, President, the duties of the office shall be performed by the Deputy Chairman, or, if the office of Deputy Chairman is also vacant, by such member of the Council of States as the President may appoint for the purpose.
(2) During the absence of the Chairman from any sitting of the Council of States the Deputy Chairman, or, if he is also absent, such person as may be determined by the rules of procedure of the Council, or, if no such person is present, such other person as may be determined by the Council, shall act as Chairman."
This Article speaks about the power of the Deputy Chairman or any other person of the Rajya Sabha to perform the functions of the Chairman, in his absence.
This Article has two clauses and it is as per the original Constitution which means it has not yet been amended even since it became effective from 1 st July, 1964.
The first clause of the Article states that in case the seat of the Chairman of the Rajya Sabha is vacant or when the Vice-President of India who is the ex-officio Chairman of the Rajya Sabha performs the functions of the President of India, then Deputy Chairman shall act as Chairman with full powers as of Chairman. This clause also states that in case, the seat of the Deputy Chairman is also vacant then any other member of the Rajya Sabha as has been appointed by the President of India, shall act as Chairman.
The second clause states that during the absence of the Chairman, the Deputy Chairman and if both are absent, then any other member shall act as Chairman and also if such a person is not available, then it is upto the Rajya Sabha to select another member to act as Chairman.
This Article is complete in itself and provides that in no case shall the post of the Chairman of the Rajya Sabha remain vacant as it is a permanent body unlike the Lok Sabha.