Mason CJ:

This appeal concerns the construction of the words "the ordinary time rate of pay of the worker (as expressed by reference to a week)" in s. 69(1)(a)(ii) of the Workers Compensation Act 1988 (Tas.) ("the Act"). The Full Court of the Supreme Court of Tasmania unanimously held that, upon the proper construction of s. 69(1)(a), the appellant ("the worker") who was relevantly employed for two eight-hour shifts each week, was to be compensated for his total incapacity for work on the basis of a 16 hour week.It rejected the argument of the worker that his compensation was to be calculated on the basis of the 38 hours per week which were the "ordinary hours of work" for a week under the industrial award which governed his employment.The question in the appeal is whether the words "as expressed by reference to a week" mean that the compensation payable to a worker is to be calculated by reference to the actual number of hours he or she ordinarily works in a week or by some other criterion and, if so, what criterion.

The factual background

The worker sustained injury on 8 September 1989 in the course of his employment as a casual labourer with the second respondent ("the employer"). The first respondent is the employer's licensed compensation insurer ("the insurer"). Initially, the worker was paid compensation on the basis of a 38 hour week.However, after a period, the employer and the insurer applied to a Workers Compensation Commissioner for a review of those payments.They sought a determination that the amount of weekly compensation to be paid to the worker was to be calculated by reference to a 16 hour week.The application was dismissed by Commissioner Sikk.An appeal against that decision to the Supreme Court of Tasmania was dismissed by Zeeman J. However, the Full Court of the Supreme Court of Tasmania allowed the appeal.

Some agreed facts were put before Commissioner Sikk.But it was conceded before Zeeman J. that two of them could not be construed literally.The effect of the agreed facts when read with the concession is as follows.On or about 6 September 1989, the employer engaged the worker as a labourer.They agreed that the worker was to be employed for eight hours on the Wednesday and Friday of each week.At all material times, other than when being paid workers' compensation, the worker was employed and paid pursuant to the terms of the Tanning Industry Award 1987, an award made pursuant to the Conciliation and Arbitration Act 1904 (Cth). Clause 9 of the award provides that, except as to casual workers and subject to certain provisos, employment is by the week. "Casual employee" is defined in cl.8 to mean "an employee (other than a regular employee) employed and paid by the day, who shall not be employed as a casual employee for more than ten days from the time of commencing employment". Clause 10 provides that an adult employee shall be paid at a rate "of pay per week". The rate varies according to the class of work on which the employee is engaged.An employee is also paid an industry loading of $13.55 per week.Clause 13 provides for the payment of casual workers.It provides:

(a) A casual worker is a worker engaged and paid as such. A casual employee for working ordinary time shall be paid per hour, one thirty-eighth of the weekly rate prescribed by this Award for the work the employee performs plus twenty percent.The employment of a casual worker may be terminated by the giving of one hour's notice by either side.

(b) A period of engagement shall not exceed ten working days continuously, provided that the period may extend beyond ten days with the written consent of the Union Branch

The construction of s. 69 of the Act

Section 69(1) of the Act provides:

Subject to this section, where total or partial incapacity for work results from an injury suffered by a worker and where the existence of such total or partial incapacity is supported by a certificate in the prescribed form from a medical practitioner, the co