The working conditions of the service are governed by an award of the Conciliation and Arbitration Commission called The Tramway Employees (Melbourne) Interim Award 1958, as amended. It contained a wage rate for a "one-man bus operator" but otherwise did not deal with the subject. The basis of jurisdiction for that award was an industrial dispute arising from a log of claims for wages and conditions of employment by the Australian Tramway and Motor Omnibus Employees Association served upon tramway and bus authorities in Victoria, South Australia and Tasmania. No one denies that an inter-State dispute arose out of the service of the log in relation to the subjects which the log covered; but it did not cover the question of the use of one-man buses at Footscray or indeed at any place. In this situation the Association on 14th March 1962 filed in the Principal Registry of the Commonwealth Arbitration Commission an application for a variation of the award. The variation sought was the addition of a clause providing as follows: "There shall be no alteration from two-man operation to one-man or from one-man to two-man without agreement with the Union, failing agreement, by order of the Commission". By way of grounds the application said that the Board had discontinued the use of two-men trams at Footscray and had substituted one-man buses. It added that the Chairman had indicated that all buses should be operated by one man and that the question had led to an industrial dispute and, further, that members of the Association were deeply concerned with the change over. After hearing representatives of the Association and of the Board, the Senior Commissioner on 20th March 1962 made the award and order of variation against which the Board now seeks writs of prohibition. It is of course evident that the jurisdiction of the Senior Commissioner to make any order was in question and no doubt the award and order of variation were made as alternatives, for their substance is the same. The validity of the award might be supported by a new dispute if it extended beyond the limits of one State while the validity of the variation might be supported by the old dispute arising from the log (which did extend beyond one State) if only something could be found in it covering the subject matter. What in substance the award and order of variation did was to direct that the Board should not without the consent of the Association or the order of the Conciliation and Arbitration Commission require an employee to operate on his own (sic) a bus on a route on which on or after Friday, 9th March 1962, trams or buses had been operated by two or more employees; provided that the right should not be affected of the Board to require an employee to operate on his own a bus on routes at a time when or in a locality where a bus or tram was so operated before Friday, 9th March 1962. The proviso preserved the Board's right to continue to man a bus with one man at times, e.g. Saturday afternoons or Sundays, when that had formerly been the practice.