It then becomes necessary to consider the effect of the challenged legislation upon medical practitioners, and there arises a question as to the proper construction of s. 16A (1). On behalf of the plaintiffs it was submitted that the words "the practitioner" in s. 16A (1) (a) (i) mean a practitioner other than an approved pathology practitioner, and it was upon this construction that counsel for the plaintiffs particularly relied in advancing the argument that the sub-section prevents medical practitioners from carrying on practice in the ordinary way and compels them, in some instances, to render services which they would not otherwise have performed. For example, it was said that the effect of the sub-section was to prevent an approved pathology practitioner who determined that a pathology service was necessary from requesting any other medical practitioner to perform that service - that is, of course, if a medical benefit were to be payable in respect of it. This would mean that a practitioner could not have the service performed by a specialist, or by his own partner, as he might otherwise have done, but would in effect be compelled to perform the service himself. I need not consider whether, if this were so, the sub-section would impose a form of civil conscription, for in my opinion the suggested construction is erroneous. The draftsman has throughout the sub-section preserved a distinction between a practitioner who is an approved pathology practitioner and one who is not. The former is expressly so described; the latter is referred to as "a medical practitioner other than an approved pathology practitioner". Where the word "practitioner" alone appears, it is intended to cover both classes. This is clearly so in the introductory words of the sub-section; if those words did not extend to approved pathology practitioners, as well as to other practitioners, they could not be read sensibly with s. 16A (1) (b), which applies where the service was determined to be necessary by an approved pathology practitioner. There is no justification for giving practitioner in s. 16A (1) (a) (i) any narrower meaning than the ordinary meaning in which the word is used in the introductory words of the sub-section. So understood, s. 16A (1) (a) (i) takes effect harmoniously with the rest of the sub-section, and there does not arise any inconsistency, repugnancy or incongruity which might justify reading into the sub-paragraph words which do not appear there. The effect of s. 16A (1) (a) is that a medical benefit will be payable in respect of a pathology service, other than a prescribed pathology service, which is rendered by or on behalf of an approved pathology practitioner in pursuance of a request addressed to that practitioner by a practitioner, whether an approved pathology practitioner or not, who had determined that the service was necessary, or by an approved pathology practitioner who had not himself determined that the service was necessary. The last-mentioned case, provided for by s. 16A (1) (a) (ii), was no doubt intended to allow an approved pathology practitioner who had been requested to perform a service, but who was unable or unwilling to do so, to request another approved pathology practitioner to perform the service, without first determining that the service was necessary. Put shortly, the effect of pars. (a) and (b) is that any practitioner, whether an approved pathology practitioner or not, may determine that a pathology service is necessary; if the practitioner who so determines is an approved pathology practitioner he may perform the service himself or by his employee (s. 16A (1) (b)) or may request another approved pathology practitioner to perform it (s. 16A (1) (a) (i)), and an approved pathology practitioner so requested may in turn request another approved pathology practitioner to perform it (s. 16A (1) (a) (ii)) and in all these cases a medical benefit will be payable. If, however, the practitioner who so determines is not an approved pathology practitioner, he must, if a medical benefit is to be payable, request an approved pathology practitioner to perform the service (s. 16A (1) (a) (i)). Properly understood, the provisions of s. 16A (1) (a) and (b) do not compel an approved pathology practitioner to do anything except that, as has been indicated, those provisions will as a matter of practicality compel some medical practitioners to seek to become approved pathology practitioners.