(dissenting).
I regret that I am unable to agree with the majority decision. In my opinion the exclusive use of the American Medical Association’s “Guides to the Evaluation of Permanent Impairment” is mandated by the terminology of Rule 13d, supra, and that as so interpreted it is not invalid as being in conflict with A.R.S. § 23-1044.
Initially I must confess some uncertainty as to exactly what the rationale of the majority opinion is, and whether it does or does not declare Rule 13d invalid and therefore unconstitutional if given a mandatory construction. Surely its validity cannot stand or fall on the sole criterion of whether a hearing officer interprets its provisions on use of the Guides as exclusive rather than permissive. To me the rule is not being given its obvious interpretation and has been completely rewritten by this Court.
The pertinent language of Rule 13d is plain and unequivocal:
“Any ratings of the percentage of functional impairment shall be in accordance with the standards for the evaluation of permanent impairment as published by the American Medical Association in ‘Guides to the Evaluation of Permanent Impairment’.” (Emphasis supplied.)
Yet the majority opinion concludes that the Rule does not “preclude the practitioners from following other guidelines or their own professional judgment”, and thus permits the hearing officer to evaluate impairment expressed in terms of medical standards which are in conflict with the American Medical Association’s (AMA) Guides. The means by which such a conclusion is arrived at in the face of the positive language of the Rule is explained to be a frustration of A.R.S. § 23-1044, since a mandatory construction, according to the opinion, would render certain awards required by the statute impossible.
This conclusion of the majority is predicated upon the theory that the exclusive use of the AMA Guides was unreasonable, and fell within constitutional prohibitions when Dr. Brooks’ medical opinion asserted that the Guides did not reflect petitioner’s true loss of hearing, and that the one published by the United States Department of Labor would have given petitioner a greater and more accurate percentage of loss. The mandatory language of the Rule is to be ignored, according to the majority, when there is medical testimony that the AMA Guides do not accurately measure the impairment.
I submit, however, that when measured against the desirability of uniformity such a contention is neither persuasive nor logical. Parenthetically, I would note the obvious fact that the evaluation of permanent impairment in any of the bodily systems covered by the AMA Guides involves subject matter that is highly complex. It would have been impossible for the Legis*295lature to lay down in advance an exact mathematical formula to which the Commission must adhere in rating impairment. As noted in Dennis v. Jordan, 71 Ariz. 430, 442, 229 P.2d 692, 700 (1951):
“ ‘ * * * legislation dealing with social and economic problems cannot be expected, and is not constitutionally required, to be of mathematical exactitude. There are bound to be twilight zones furnishing support to critics who cavil at the want of scientific precision in the law. * * * Equitable Credit and Discount Co. v. Geier, 342 Pa. 445, 21 A.2d 53, 56.
It has been readily observable, even to my inexperienced eye, that such scientific precision is not available in the medical profession either. Through Rule 13d the Industrial Commission of Arizona, in adopting the AMA Guides as the standard through which medical opinions evaluating permanent impairment should be stated, has done nothing more than attempt to aid its own function in resolving conflicts in medical evidence.
Doctors are needed to testify as to the amount of loss of physical functions, and may give an opinion as to that ultimate fact, as such matters are wholly outside the knowledge of the trier of fact. They may also express the loss in terms of a percentage of the full functioning of the applicant before the injury occurred. See Hoffman v. Brophy, 61 Ariz. 307, 149 P.2d 160 (1944). The adoption of the AMA standards by the Industrial Commission was obviously an effort to make such percentage ratings uniform. Undoubtedly there are other rating standards, such as that of the United States Department of Labor, some of which would rate the hearing loss of the petitioner here at a lower level than that provided by the AMA Guides, and others which would rate it higher.
We are now handing the hearing officer the nebulous mandate that “where the exclusive application of the AMA Guides would frustrate the purpose of the statute (A.R.S. § 23-1044), the word ‘shall’ in the rule (13d, Rules of Procedure for Workmen’s Compensation Hearings) is interpreted as permissive, rather than mandatory.” Apparently this frustration will occur when a doctor has testified that the Guides do not accurately measure the impairment and expresses an opinion that another guide is better.
This principle places the standard to be used wholly in the hands of the individual doctor. What if another physician were to testify that the AMA Guides did constitute the more accurate standard ? Is Rule 13d then to control or will this vary from hearing officer to hearing officer? Clearly, such a construction gives the rule a “yo-yo” effect, dependent for its validity upon the absence of medical opinion asserting the inaccuracy of the Guides.
Moreover, I can find no language in A.R.S. § 23-1044 prohibiting adoption by the Industrial Commission of a mandatory and exclusive standard for rating the statute’s complex scheme for permanent impairment. To the contrary, § 23-1044G provides for the adoption of a schedule and rules to govern the rating process. In claiming that there is such prohibiting language, the majority opinion has merely pointed to an abstract interpretation of the statute that petitioner has a right to full compensation for his true hearing loss.
What the majority opinion overlooks is that the Industrial Commission has stated, by its use of Rule 13d, that petitioner did get full compensation for his hearing loss when the AMA Guides rated that hearing loss at 11 per cent.
I find no conflict in the statute, or any constitutional infirmity in the exclusive use of the AMA Guides, by virtue of the fact that the doctor here felt that they did not provide an accurate rating of the hearing loss and that another guide would be more exact. That an injustice may occur in a given fact situation does not per se render the controlling statute or rule unconstitutional, nor does it justify amendment by judicial fiat. See, 16 Am.Jur.2d, Constitu*296tional Law §§ 160, 162. The extent and character of rules and regulations of an administrative body must be fixed in accordance with common sense, Haggard v. Industrial Commission, supra.
In the preparation of this dissent I have devoted considerable time to a study of the AMA Guides, but do not now presume to understand their performance in terms of accuracy or comprehensiveness. While they obviously enjoy an empirical stature, I haven’t the slightest idea as to the wisdom of their adoption and use, or the fairness of their application in the instant case. But the province of this Court is to interpret the record as we find it, and in that record I find no justification for telling the Industrial Commission that the plain terminology of Rule 13d is unreasonable ; or that the Commission cannot set the boundaries ■ and chart the course for rating physical impairment following an industrial injury, by directing the physicians to use the same compass.
It is perfectly logical and reasonable that the Industrial Commission has determined that there should be only one standard by which to measure impairment. Without a required single standard as a basic premise, it would be difficult to ascertain whether two doctors were differing as to their appraisal of a particular condition or whether they were merely describing exactly the same condition in varying ways. Rule 13d provides a standardization among the medical profession, so that the hearing officer is able to comprehend the basis upon which medical witnesses are testifying. I submit that a uniform system and the resultant equality engendered by it is to be preferred. It seems ironic that, to me at least, Rule 13d was obviously designed to stop the exact practice (multiple standards) which the majority opinion now espouses as essential to retain the Rule’s validity.
Since there is a complete paucity of de-cisional law on the issue involved here, it might be wise, at this juncture, to defer to certain language contained within the preface of the AMA Guides themselves:
“It is . important for him [the physician] to have the necessary authoritative material to assist him in competently fulfilling his particular responsibility — the evaluation of permanent impairment. It is the purpose of this and other reports of the Committee on Rating of Mental and Physical Impairment to correct a past confusion of terms and to provide a series of practical guides to the evaluation of various types of permanent impairments. (Emphasis supplied.)
* * * * * *
“Competent evaluation of permanent impairment requires adequate and complete medical examination, accurate objective measurement of function, and the avoidance of subjective impressions and such factors as age, sex, or employability.”
The observations and conclusions of Dr. R. Gray on the adoption of the Guides is perhaps apropos here also:
“The A.M.A. Committee on Medical Rating of Physical Impairment was first created in September of 1956 with authorization to establish practical guides for an evaluation of impairment ratings. The first guide to appear in the Journal of the American Medical Association presented ratings for illnesses and injuries affecting the Extremities and Back. Since that time, twelve other guides covering other body systems have been compiled and published in various issues of JAMA.
In 1971, all of these guides were published in a single volume. In addition, the older guides were reviewed and updated where necessary with information accumulated and techniques developed since their inception.” 4 R. Gray, M.D., Attorneys’ Textbook of Medicine ¶ 181.11 at p. 181-14 (3rd Gordy ed. 1973). (Emphasis supplied.)
* * * * * *
“Various medical societies and individual physicians have proposed several meth*297ods of evaluation. However the first attempt to formulate a practical as well as comprehensive guide to determine permanent impairment of individual body systems in regard to the whole man was made by the AMA Committee on Medical Rating of Physical Impairment.” 4 R. Gray, supra at 181-15.
Expressing the caveat that the AMA Guides relate to evaluation of physical disability only, the National Commission on State Workmen’s Compensation Law termed them “a welcome contribution”. Major Conclusions and Recommendations, 1 Workmen’s Comp.L.Rev. 657 (1974).
It is obvious that Rule 13d was not blindly adopted. It is also obvious that at the time of its adoption there were other and differing guides in 'existence for perusal and consideration by the Commission, and yet only one was chosen and that one was given exclusivity as representing the accumulated knowledge of the prestigious medical profession. If the superiority of the AMA Guides had to be proved in each hearing, any pretense of a uniform system would be lost.
It cannot be unconstitutional that the Commission has required that one doctor may not speak in terms of apples while another is talking in terms of oranges. If petitioner desires a more liberal rating system, his remedy is to seek adoption of such by the Commission and not to challenge the validity of the existing system in Court. The ensuing result of the opinion rendered today might well be a Pandora’s Box of uncertainty in an area where uniformity and consistency are to be sought. The decision changes a system which has apparently been rigidly adhered to by the Industrial Commission in Arizona since the adoption of Rule 13d in 1970. More importantly perhaps, it erodes further a judicial system already under attack for usurping legislative and administrative functions.
I would affirm the award.