Opinion
MANUEL, J.Plaintiff Donald A. Miller, a licensed physician and surgeon, appeals from a judgment denying his petition for a writ of mandate sought to compel defendant Eisenhower Medical Center, a private, nonprofit hospital corporation, to grant him staff membership and privileges at its hospital facility.
The cause was submitted to the trial court on the transcripts of hearings before defendant’s judicial review and appellate review committees as well as various letters and documents. The underlying facts, as appearing therefrom, were in substance as follows:
Plaintiff, a board certified family physician and a member of the American Academy of Family Physicians, has been practicing in Indio, *619California since 1970. He first sought staff membership at the Eisenhower Medical Center, a private hospital in Palm Desert owned and operated by defendant, in 1971, but that application was subsequently withdrawn by him and he reapplied in 1972. After denial of the 1972 application he again reapplied in 1974. Again the application was denied, and plaintiff’s subsequent request for a hearing pursuant to the medical staff bylaws was also denied as being untimely.1
In 1975, plaintiff again reapplied for medical staff membership at Eisenhower. Along with his application he submitted by letter the names of 25 physicians whom the medical executive committee of the hospital might contact for recommendations concerning his suitability for membership.2 After soliciting comments from all of plaintiff’s references,3 the medical executive committee informed plaintiff that his application had been denied “on the basis of recommendations received from references furnished by you in your letter.... ”
Plaintiff thereupon made timely application for a hearing before the judicial review committee. (See fn. 1, ante.) He also requested copies of the recommendations upon the basis of which his application had been denied. He was provided with a compilation of the responses made to each question (see fn. 3, ante) but was denied the names of the physicians who had provided particular responses on the ground that confidentiality was necessary “[i]n order to maintain a viable application process,...”
At the hearing before the judicial review committee plaintiff appeared on his own behalf; the medical executive committee was rep*620resented by one of its members. The latter reported that plaintiff's references gave him “good support from the standpoint of your professional competence, your knowledge and [the] adequacy of your training” but that the committee felt that plaintiff “came up wanting” with respect to the opinions received on the question whether he would be an asset to the medical staff.4 (See fn. 3, ante.) Plaintiff was permitted to present four medical doctors as witnesses on his behalf. All testified favorably regarding plaintiff’s medical competence; each was of the opinion that plaintiff would be an asset to the medical staff. One indicated that he was sometimes “a little impetuous about things which he wanted to be done” concerning staff practices and procedures but that “in the long run most of these ideas were very constructive ideas.” Another, responding to a question concerning possible areas of conflict in “interpersonal relationships” with others, stated that although he had heard “rumors” he had himself neither observed nor experienced any such conflicts. A third, characterizing plaintiff as “a controversial person,” went on to explain that he had reference to his tendency to express himself quite forcefully and vigorously in the evaluation of the competence of another physician, for example, or the running of a medical institution.
Plaintiff was also questioned at this hearing regarding a number of other matters, including the circumstances surrounding his departure from an internship program at the Cook County (Illinois) hospital some 14 years earlier. Protesting that he had received no notice that the latter subject was to be a matter of concern at the hearing, and that therefore he was not prepared to provide an exact account of it, he nevertheless indicated that “a definite disagreement of some kind,” the details of which he could not recall, had precipitated his departure from the program at Cook County Hospital and the resumption and completion of his internship at another institution.
The judicial review committee upheld the medical executive committee’s decision, stating that its conclusion was based “upon the determination that sufficient doubt exists concerning Doctor Miller’s *621ability to work with others as stated in Article III, Section 2 of the Medical Staff Bylaws.”5
Plaintiff thereupon appealed the decision of the judicial review committee to the medical center’s board of trustees (board), as provided in the bylaws.6 He requested and was granted the right to be represented by counsel at the hearing and to present witnesses in his behalf. Prior to the hearing his counsel requested that he be provided with the names of those doctors who had provided the negative recommendations reflected in the compilation previously furnished to plaintiff. Counsel for the board, responding to this request, indicated that these names would not be disclosed for reasons of confidentiality. His letter also stated: “The basis upon which Dr. Miller has been refused admission to the Medical Staff was his failure to comply with Section 2(a) of the Medical Staff By-laws and in particular, his failure to document his good reputation and ability to work with others. The following facts were presented at the hearing or will be presented at the appellate review to augment the record. [¶] 1. The failure to disclose at the hearing the reasons for his termination from the internship at Cook County Hospital. This was withheld despite direct questions regarding this. [¶] 2. The reasons for the termination of the residency [sic] at Cook County Hospital which directly relate to the qualifications in Section 2(a). [¶] 3. The letter from Martin S. Gittleman, Administrator of Indio Community Hospital, regarding Dr. Miller’s ability to work with others. [¶] 4. A letter setting forth gross inaccuracies which Dr. Miller wrote to the Compre*622hensive Health Planning Association which included an intemperate assault on Eisenhower Medical Center. ... [¶] 5. The existence of a sufficient number of negative comments or lack of comments on responses from Dr. Miller’s references which indicate his inability to work and cooperate with others and, therefore results in his failure to meet Medical Staff requirements at the present time.”
At the appellate review hearing two additional doctors were called by the medical executive committee. Each testified that plaintiff had a reputation for getting along poorly with his colleagues. One stated that he “creates dissension” and “has relatively few friends in the community,” the other that he “does not get along with most members of the medical community.” Neither, however, indicated that he had personally had any difficulty working together with plaintiff in the care of patients. Each of these doctors had had a prior business relationship with plaintiff: one had been associated with plaintiff in the ownership of a hospital and had particular objections concerning plaintiff’s having contracted to run the emergency room at a competing hospital; the other had been associated with plaintiff in practice. Three of the four doctors who had testified in plaintiff’s behalf before the judicial review committee gave substantially similar testimony at the appellate review hearing. Again none of these doctors had ever experienced any difficulty with plaintiff in mutual care of patients.
The matter of termination of plaintiff’s 1961-1962 internship was also raised. A letter from the medical director of the Cook County Hospital was introduced; it was therein indicated that plaintiff had been asked to leave before the completion of his internship, which was subsequently completed at another hospital, “because he did not assume his responsibilities to the hospital and his patients.” Apparently a second letter from the same party was also presented, this letter explaining that the circumstances of plaintiff’s dismissal involved his taking an unauthorized one-week vacation.7 Plaintiff was examined at some length by his own and opposing counsel concerning the details of the incident and his alleged inability to recall them at the judicial review committee hearing. Again he protested that he had been given no notice of any kind prior to the latter hearing that the matter of his internship was to be raised there or had been a matter of concern to the medical executive committee in its denial of his application.8 He indicated that he had *623answered “to the best of my ability but.. .just couldn’t recall the exact details” at that time, “[s]ince I hadn’t known that it was a problem.” Having refreshed his memory in the interim by means of contacting certain parties involved, he stated that he now had a vivid recollection of the matter and was fully prepared to respond to questions concerning it. He proceeded to do so.
The medical executive committee also introduced a letter which plaintiff had directed the preceding summer to the executive director of the Comprehensive Health Planning Association. In this letter plaintiff voiced strenuous objection to the granting of an application for more hospital beds by one of the area hospitals, suggesting at one point that opposition to the application had been silenced pursuant to a secret agreement between the subject hospital and the Eisenhower Medical Center to suppress relevant information. The letter also contained derogatory remarks concerning the establishment of the Eisenhower Medical Center.9 Plaintiff was questioned extensively about this letter, his motivation for writing it, and the factual bases upon which its allegations were grounded. He conceded that certain statements contained within it might have been inaccurate or “presumptuous” but indicated that he had been upset at the time of its writing by what he perceived to be a plot to favor certain hospitals at one end of the Coachella Valley at the expense of another hospital having adequate bed space in Indio.
Following the hearing on March 12, 1976, plaintiff was informed by letter that the board had “determined that substantial evidence was produced, at both your Judicial Review Committee hearing and the hearing before the Appellate Review Committee of this Board, to support the previous conclusion of the Medical Staff that you do not meet *624the requirements for membership on the Medical Staff of Eisenhower Medical Center. [1i] Therefore the Board of Trustees has affirmed the action of- the Medical Staff and denied your application for such membership.”
On March 29, 1977, more than a year after the date of the aforesaid letter, plaintiff commenced the instant proceeding. The trial court concluded that the requirements for membership were rational and not arbitrary, capricious, or contrary to public policy; that all proceedings had been conducted in a manner comporting with fair procedure; that the rejection of plaintiff had not resulted from arbitrary or discriminatory motivation or conduct; that there was substantial evidence in support of the determination made; and that the defense of laches was applicable. Plaintiff appeals from the ensuing judgment denying the petition.
I
We first address the issue of laches.
As we pointed out in Conti v. Board of Civil Service Commissioners (1969) 1 Cal.3d 351 [82 Cal.Rptr. 337, 461 P.2d 617], the affirmative defense of laches requires unreasonable delay in bringing suit “plus either acquiesence in the act about which plaintiff complains or prejudice to the defendant resulting from the delay.” (Id., at p. 359, fns. omitted.) Prejudice is never presumed; rather it must be affirmatively demonstrated by the defendant in order to sustain his burdens of proof and the production of evidence on the issue. (Id., at p. 361.) Generally speaking, the existence of laches is a question of fact to be determined by the trial court in light of all of the applicable circumstances, and in the absence of manifest injustice or a lack of substantial support in the evidence its determination will be sustained. (See Rouse v. Underwood (1966) 242 Cal.App.2d 316, 323 [51 Cal.Rptr. 437]; Teixeira v. Verissimo (1966) 239 Cal.App.2d 147, 158 [48 Cal.Rptr. 496]; see also Concerned Citizens of Palm Desert, Inc. v. Board of Supervisors (1974) 38 Cal.App.3d 257, 265-266 [113 Cal.Rptr. 338]; McClung v. Saito (1970) 4 Cal.App.3d 143, 152 [84 Cal.Rptr. 44].)
We have also suggested that in cases seeking review of an administrative decision there may be substantial reasons for supporting a finding of laches for delays “far less than” the period of the applicable statute of limitations. (Conti, supra, at p. 357, fn. 3; see also Deering, Cal. Administrative Mandamus (Cont.Ed.Bar 1966) § 8.5, pp. 125-127; id. (Cont.Ed.Bar Supp. 1977) §§ 8.5-8.5A, pp. 86-88.)
*625Plaintiff urges that the trial court’s finding of laches lacks substantial support in the record. It is argued that even if the one-year- and-seventeen-day delay between the board’s final decision and the commencement of suit be deemed unreasonable, the record offers no basis upon which the second element of the defense—i.e., either acquiescence on his part or prejudice to the defendant—could reasonably be found to exist. It is notable in this respect that, as indicated above, the matter was submitted solely on the administrative record; defendant made no effort to introduce evidence of acquiescence or prejudice.10 The record contained nothing indicating acquiescence on plaintiff’s part to the board’s decision.
With respect to the matter of prejudice to the defendant, however, defendant calls our attention to provisions in the bylaws to the effect that all staff appointments are of one year’s duration with reappointment subject to annual review through a process involving a report by the departmental chairman. These provisions, it is argued, are clearly intended to insure that all physicians admitted to the staff currently meet the standards for admission. Defendant concludes that plaintiff, by delaying more than a year before seeking judicial review of the board’s decision, presented the court with an application and evidence which was necessarily “stale” and, as such, could not possibly form the basis for current admission. Thus, it is urged, prejudice clearly appears.
We do not agree. With respect to the application form itself, which is a part of the instant record, it appears that the form filled out by plaintiff at the time of his original application in 1971 was thereafter used by defendant as the basis of all subsequent applications—i.e., 1972, 1974, and the application here involved, 1975.11 Insofar as matters aliunde the application form are to be considered, there is no showing made that members of the medical staff seeking reappointment are required to provide any new information or additional documents concerning their qualifications each year, nor is it suggested or offered to *626be shown that any relevant changes have occurred in plaintiff’s qualifications. The record reflects no recent alterations in the appointment process or in the situation regarding availability of staff positions. Defendant, in short, simply asks that we presume prejudice. This we may not do. The trial court’s finding of laches, we conclude, is not supported by the evidence.
II
Plaintiff, relying principally on cases such as Rosner v. Eden Township Hospital Dist. (1962) 58 Cal.2d 592 [25 Cal.Rptr. 551, 375 P.2d 431], Martino v. Concord Community Hosp. Dist. (1965) 233 Cal.App.2d 51 [43 Cal.Rptr. 255], and Wyatt v. Tahoe Forest Hospital Dist. (1959) 174 Cal.App.2d 709 [345 P.2d 93], argues that the standard for medical staff membership under which he was excluded (see fn. 5, ante) is so vague and uncertain as to provide a substantial danger of arbitrary or discriminatory application, and that it must therefore be held invalid. Recognizing that the cited cases have involved public rather than private hospital institutions, he urges that their teaching must be applied in the case of private hospitals as well to preclude the adoption of standards for admission to staff membership whose terms are unreasonably susceptible of arbitrary or discriminatory application. The standard here in question, he argues, suffers from just this vice.
We agree—and indeed we do not understand defendant to do otherwise—that even a private hospital institution may not adopt rules for the admission to staff membership which permit exclusion on an arbitrary or irrational basis. As we have stated in a similar context, “[i]n addition to requiring a fair procedure, the common law decisions establish that expulsion from an association cannot properly rest upon a rule which is substantively capricious or contrary to public policy.” (Pinsker v. Pacific Coast Society of Orthodontists (1974) 12 Cal.3d 541, 553 [116 Cal.Rptr. 245, 526 P.2d 253].) A similar rule is applicable to private hospitals. (See Willis v. Santa Ana etc. Hospital Assn. (1962) 58 Cal.2d 806, 810 [26 Cal.Rptr. 640, 376 P.2d P.2d 568]; Blank v. Palo Alto-Stanford Hospital Center (1965) 234 Cal.App.2d 377, 383, fn. 2 [44 Cal.Rptr. 572].) In the words of a recent decision of the Court of Appeal, stating the proposition in its negative aspect, “[A] rule or policy decision of general application adopted by the governing authority of a hospital or professional society impinging on the right of a physician to practice his or her profession fully will not be set aside by a court unless it is substantively irrational, unlawful or contrary to established *627public policy or procedurally unfair.” (Lewin v. St. Joseph Hospital of Orange (1978) 82 Cal.App.3d 368, 385 [146 Cal.Rptr. 892], italics added.) By the same token, and as the cases we have cited attest, a rule governing the admission of qualified physicians to staff membership in any hospital,12 whether public or private, cannot stand if it establishes a standard for admission which is substantively irrational or otherwise unreasonably susceptible of arbitrary or discriminatory application.13 We turn to the question whether the rule before us can be said to suffer from this failing.
Plaintiff’s specific contention relates to that aspect of the subject rule which permits exclusion from staff membership solely on the basis of a physician’s “ability to work with others.” In this respect, he urges, the subject rule is similar to the bylaw involved in our Rosner case,14 supra, which, we there indicated, posed a substantial danger of application “as a subterfuge where considerations having no relevance to fitness are present.” (58 Cal.2d at p. 598.) Here, he urges, the bylaw in question poses the same danger, permitting the exclusion of one of otherwise impeccable qualifications on the basis of personal qualities which, while perhaps offensive or abrasive to some, lack any demonstrable relationship to capability or fitness.
*628We do not agree. Not only is Rosner distinguishable on technical grounds,15 but the bylaw there involved bears marked differences from the one which here concerns us. In the first place the Rosner bylaw spoke in terms of “apparent ability to get along with others,” whereas the instant bylaw places its focus on thfe “ability to work with others.” We perceive a substantial distinction between these two requirements, the second shifting the focus from general compatibility to the ability to cooperate in the performance of hospital functions. More significantly, the bylaw here in question, unlike that in Rosner, must in our view be read to demand that there be a demonstrable nexus between the applicant’s ability to “work with” others and the effect of that ability on the quality of patient care provided. What is required, in short, is that an applicant demonstrate that he has the ability to “work with” others in the hospital environment in a manner which, in the words of the bylaw, will insure “that any patient treated by [him] in the hospital will be given a high quality of medical care. ...”
We do not believe that this bylaw, as so construed, may be said to suffer from the substantive irrationality of which plaintiff complains. (Cf. Morrison v. State Board of Education (1969) 1 Cal.3d 214, 230-233 [82 Cal.Rptr. 175, 461 P.2d 375].) It cannot be denied that the providing of high quality patient care is, quite properly, the primary concern of all hospital institutions. The governing authority bears the responsibility for assuring that this goal is achieved to the greatest extent possible, and its decisions relating to medical staff must take into account all factors which have a legitimate relationship to it. We are not prepared to say that an applicant’s ability to work with other medical personnel in the hospital setting may not have a clear effect on the *629level of patient care provided. (See generally, Note, Hospital Staff Privileges: The Need for Legislation (1965) 17 Stan.L.Rev. 900, 916.) What we do say, however, is that in order to avoid the danger of arbitrary and irrational application and the concommitant danger that such a bylaw may be used “as a subterfuge where considerations having no relevance to fitness are present” (Rosner, supra, at p. 598), it must be read to demand a showing, in cases of rejection on this ground, that an applicant’s inability to “work with others” in the hospital setting is such as to present a real and substantial danger that patients treated by him might receive other than a “high quality of medical care” at the facility if he were admitted to membership.
Defendant urges that we need not go so far. Relying on a number of decisions from other jurisdictions—most notably that in Huffaker v. Bailey (1975) 273 Ore. 273 [540 P.2d 398]—it argues in essence that a physician’s ability to “work with others” in the hospital setting has an inherent effect on the level of patient care provided, and that in the absence of a manifest abuse of discretion the decision of the hospital must be sustained in all cases where a reduction in such ability is shown. We do not agree. It is quite true, of course, that certain forms of disruptive or noncooperative conduct may have an adverse effect upon the level of patient care; we find ourselves in full accord with language to this effect in Huffaker and certain other cases.16 We think it also clear, however, that a concept so broad as “working with others” might well be deemed to include other forms of conduct which, while assertive and even abrasive in character, cannot be shown to present a significant danger that the level of patient care will be adversely affected. As we pointed out in Rosner, “[i]n asserting their views as to proper treatment and hospital practices, many physicians will become involved in a certain amount of dispute and friction, and a determination that such common occurrences have more than their usual significance and show temperamental unsuitability for hospital practice of one of the doctors is of necessity *630highly conjectural.” (58 Cal.2d at p. 598.) The subject bylaw, if interpreted in the manner suggested by defendant, would permit exclusion of an otherwise qualified physician on just such “conjectural” grounds. Accordingly, and in order to preclude this danger, we must insist upon the narrower interpretation we have indicated.17
Ill
Turning to the record, we there encounter what must be termed a state of considerable confusion concerning the content of the standard to be applied. On the one hand it appears to have been the view of the medical executive committee that a showing of significant limitations in an applicant’s ability to “get along” with other hospital personnel was sufficient in and of itself to justify rejection under the subject bylaw. On the other hand it appears to have been plaintiff’s view that the only showing upon which the subject bylaw would permit rejection on grounds of incompatibility would be one indicating the applicant’s inability to work effectively and harmoniously with other doctors in the joint care of a particular patient. Faced with these conflicting points of view, the members of the two deliberative bodies involved (i.e., the judicial review committee and the appellate review committee) at several points manifested uncertainty as to the correct standard to be applied.18
*631The evidence reflected this divergence of views. The medical executive committee, generally speaking, concentrated its efforts on establishing that plaintiff, through what was frequently termed the more “controversial” or “flamboyant” aspects. of his personality, had succeeded in alienating a substantial segment of the local medical community. Emphasis was placed on certain business dealings which plaintiff had had with other doctors, the history of his association in practice with other doctors, his alleged propensity for litigation, and his readiness to express his views on the treatment practices of other doctors and hospital administrative matters. No effort was made, however, to establish any direct19 link between these considerations and their potential effect on patient care. Plaintiff, on the other hand, directed his efforts toward establishing his level of medical competence; he also sought to establish, particularly through cross-examination of hostile witnesses, that his personality traits had never resulted in perceived difficulty in the mutual care of individual patients.
The bylaw provision here before us, as we have indicated, must be read to preclude the rejection of an otherwise qualified physician from *632medical staff membership unless it can be shown that he manifests an inability to “work with others” in the hospital setting which, by reason of its particular character, presents a real and substantial danger that patients treated by him at the facility might receive other than a “high quality of medical care” if he were admitted to membership. This standard, in our view, is neither so broad as defendant conceives it nor so narrow as plaintiff asserts. On the one hand, there may well be circumstances in which a doctor’s limited ability to “work with” other hospital personnel, although it results in no demonstrable conflict in the joint care of individual patients, might nevertheless be shown to have a clear adverse effect on the overall “quality of medical care” offered by the facility—and therefore on the quality of care to be offered the applicant’s patients as well. On the other hand, we do not believe that that nexus may be presumed. The fact that a physician seeking admission to staff membership is shown to manifest characteristics of personality which other staff members or administrators find personally disagreeable or annoying is not in itself enough, in our view, to justify rejection under the subject bylaw provision. An otherwise competent physician, although considered “controversial,” outspoken, abrasive, hypercritical, or otherwise personally offensive by some of his hospital colleagues, may nevertheless have the ability to function as a valuable member of the hospital community and should not be denied the opportunity to do so as a result of personal animosities or resentments alone. To permit such application of the bylaw in question would, in the words of Rosner, pose a substantial danger of application “as a subterfuge where considerations having no relevance to fitness are present.” Rejection on this basis can be permitted, therefore, only when it can be shown that the applicant’s ability to work with others in the hospital setting is limited in a manner which would pose a realistic and specific threat to the quality of medical care to be afforded patients at the institution.
As we have suggested, the record before us falls far short of establishing such a showing. The sole attempt that was actually made to link plaintiff’s personality characteristics to a foreseeable concrete effect on the level of patient care is comprised of two leading questions couched in vague generalities. (See fn. 18, ante.) Although “[t]he common law requirement of a fair procedure does not compel formal proceedings with all the embellishments of a court trial... nor adherence to a single mode of process” (Pinsker v. Pacific Coast Society of Orthodontists, supra, 12 Cal.3d 541, 555), we must insist that a hospital seeking to withhold staff membership from an otherwise qualified physician on the ground we here consider must be prepared to come forward with evi*633dence of a more concrete and specific nature—directed toward establishing the indicated link between conduct and potential effect— than that we here consider.
It is suggested, however, that even if the determination reached by defendant lacks substantial support on the basis of the evidence above discussed, there is ample additional evidence in the record to support it. Particular attention is drawn to two areas of inquiry reflected in the record which, it is asserted, provide a basis on which defendant could properly have determined that plaintiff’s veracity was subject to question—namely (1) that concerning his faulty recollection of the details surrounding the termination of his internship at Cook County Hospital (see fns. 7 and 8, ante, and accompanying text) and (2) certain allegedly libelous and untrue statements made by plaintiff in his letter to the Comprehensive Health Planning Association (see fn. 9, ante, and accompanying text). It is urged, in short, that an applicant’s veracity is certainly a matter which a hospital board can properly consider in determining whether the requirements for staff membership have been met, and that because the instant record reveals a substantial basis for determining that plaintiff had been untruthful in the indicated respects, the decision denying staff membership must be upheld.
We cannot agree. In the first place we are troubled by questions of fair notice. As we have pointed out, the administrative proceedings herein were initiated by plaintiff in the first instance after he was informed that his application for staff membership had been rejected “on the basis of recommendations received from references furnished” by him in the letter accompanying his application. The compilation of recommendations which plaintiff subsequently received contained nothing relating to his veracity, although there were several which termed him “controversial” or “disruptive.” The latter characterizations formed the focus of the judicial review committee hearing which followed; it was at this hearing that questions concerning plaintiff’s internship were initially raised—and it was here that there occurred the temporizations on which defendant now places such heavy emphasis. The judicial review committee upheld the prior rejection, basing its conclusion “upon the determination that sufficient doubt exists concerning Doctor Miller’s ability to work with others. . .. ” Upon appealing this determination, plaintiff was informed by letter that the basis ior refusal was his “failure to document his good reputation and his ability to work with others” (italics added); it was also indicated that the matter of his internship, as well as the matter of his letter to the Comprehensive *634Health Planning Association, would be explored at the appellate hearing—as it was.
As we indicated in our second Pinsker decision {supra, 12 Cal. 3d 541), the common law requirement of fair procedure “may be satisfied by any one of a variety of procedures which afford a fair opportunity for an applicant to present his position. As such, this court should not attempt to fix a rigid procedure that must invariably be observed. Instead, the associations themselves should retain the initial and primary responsibility for devising a method which provides an applicant adequate notice of the ‘charges’ against him and a reasonable opportunity to respond.” (12 Cal.3d at p. 555, fn. omitted, italics added.) Here the form of notice adopted upon plaintiff’s initial rejection by the medical executive committee, while in our view adequate as far as it went, fell short of advising him of the full scope of the inquiry to be pursued at the judicial review committee hearing. By stating that he had been rejected “on the basis of recommendations received from references furnished by you in your letter of September 3, 1975” (italics added), it had the effect of suggesting to him that the focus of any further proceedings requested by him would be upon those recommendations and that his preparation for such proceedings might properly adopt a similar focus. In these circumstances, we think, it lies ill in the mouth of defendant to suggest that any uncertainty or vagueness appearing in his answers at the judicial review committee hearing on the subject of his internship, which had occurred some 14 years previously, is to be interpreted as mendacity and guile on his part.
There is yet another reason why we think that defendant’s substantial evidence argument—premised on what it perceives as evidence of impaired veracity in this record—must be rejected. As we have pointed out, the dominant focus of all of the administrative proceedings with which we are here concerned was that of plaintiff’s ability to work with other hospital personnel in a manner which would not impair the quality of medical care offered. The attention of all participants in the proceedings—the contending applicant and medical executive committee, their respective counsel, and members of each of the two deliberative bodies involved—was trained upon this issue in a manner leaving little doubt as to its centrality. As we have pointed out, however, this attention was largely diffused and misdirected by a failure to comprehend the true nature of the standard to be applied. To uphold the determination thus made on the basis of evidence which lay outside of, *635or at least at the periphery of, this major thrust of the inquiry would not, we think, be appropriate in the circumstances.
It is well settled, of course, that in cases involving the imposition of a penalty or other disciplinary action by an administrative body, when it appears that some of the charges are not sustained by the evidence, the matter will be returned to the administrative body for redetermination in all cases in which there is a “real doubt” as to whether the same action would have been taken upon a proper assessment of the evidence. (See Bonham v. McConnell (1955) 45 Cal.2d 304, 306 [288 P.2d 502]; Cooper v. State Bd. of Medical Examiners (1950) 35 Cal.2d 242, 252 [217 P.2d 630, 18 A.L.R.2d 593]; see also English v. City of Long Beach (1950) 35 Cal.2d 155, 159-160 [217 P.2d 22, 18 A.L.R.2d 547]; cf. Byrd v. Savage (1963) 219 Cal.App.2d 396, 402-403 [32 Cal.Rptr. 881]; Strode v. Board of Medical Examiners (1961) 195 Cal.App.2d 291, 303-304 [15 Cal.Rptr. 879]; Steele v. L.A. County Civil Service Com. (1958) 166 Cal.App.2d 129, 139 [333 P.2d 171]; Mast v. State Board of Optometry (1956) 139 Cal.App.2d 78, 91-93 [293 P.2d 148].) A distinction has been drawn, however, between cases of this kind and those involving an application for a license or other privilege, it being suggested that in such cases careful scrutiny of this nature is not requisite. (See especially Sica v. Board of Police Commissioners (1962) 200 Cal.App.2d 137, 141 [19 Cal.Rptr. 277]; see also Hora v. City & County of San Francisco (1965) 233 Cal.App. 2d 375, 379 [43 Cal.Rptr. 527].) Even in these cases, however, it is intimated that the existence of a “real doubt” as to the probable determination of the administrative body upon a proper view of the evidence will necessitate a redetermination. (See Sica, supra, at pp. 142-146; Morris v. Unemployment Ins. Appeals Bd. (1973) 34 Cal.App.3d 1002, 1009 [110 Cal.Rptr. 630]; see also Deering, Cal. Administrative Mandamus (Cont.Ed.Bar 1966) § 5.41, p. 59.)
We believe that the instant case is one in which the principle of “real doubt” should properly be applied. As we have indicated, the dominant focus of these proceedings was drastically blurred by a failure of the deliberative bodies involved—and indeed the parties and their counsel as well—to properly understand and apply the hospital’s own standards for admission to staff membership insofar as they concerned an applicant’s ability to “work with” others. Although evidence was also presented on other matters, our reading of the record as a whole raises a significant and real doubt in our minds as to whether the deliberative bodies involved, had they been faced with only such other evidence, *636would have reached the result that they did. In any case it is clear that the misconception concerning the proper content of the hospital’s standards for admission resulted in a severe misapprehension of the kind and quality of plaintiffs qualifications for admission. In these circumstances, we think the proper course is to return the matter to defendant in order that it may undertake further administrative proceedings directed to the assessment of plaintiffs qualifications for admission to its medical staff in light of a proper interpretation of its standards.
The judgment is reversed with directions to issue a peremptory writ of mandate directing defendant to set aside its decision denying plaintiffs application for medical staff membership and to either grant that application or, in the alternative, to undertake further proceedings in light of this opinion.
Bird, C. J., Tobriner, J., Richardson, J., and Newman, J., concurred.
The bylaws provide that a hearing must be requested within 10 days of the notice of denial. Apparently plaintiff was not explicitly made aware of his right to a hearing or the requisite period for requesting it upon the denial of his 1974 application, although he was so informed following denial of the 1975 application which here concerns us. (See Westlake Community Hosp. v. Superior Court (1976) 17 Cal.3d 465, 477-478 [131 Cal.Rptr. 90, 551 P.2d 410].)
Apparently this was a substantially greater number of references than was customarily submitted by applicants for staff membership. In response to a question at the subsequent judicial review committee hearing plaintiff indicated that in view of his previous rejections he had thought it prudent to provide references from all fields of medicine which were involved in his practice.
The references were asked the following questions: (1) “How long have you known this physician?”; (2) “What are his professional capabilities?"; (3) “Please provide information on his competence as a physician"; (4) “Do you feel he would be an asset to our Medical Staff?”; and (5) “Comments.”
Out of 22 responses to this question approximately 15 were favorable, some enthusiastically so. Of the seven remaining responses, four were clearly unfavorable. Two of these answered simply: “No.” One answered: “Very controversial person. Has been disruptive in other situations.” One answered: “I have no knowledge of Dr. Miller’s plans regarding [Eisenhower Medical Center]. I do have knowledge of several physicians whose feelings are that they would think not.”
There were no adverse comments concerning plaintiff’s professional capabilities or his competence as a physician.
The indicated section provides in relevant part as follows: “Only physicians and dentists licensed to practice in the State of California, who can document their background, experience, training and demonstrated competence, their adherence to the ethics of their profession, their good reputation, and their ability to work with others, with sufficient adequacy to assure the Medical Staff and the Board of Trustees that any patient treated by them in the hospital will be given a high quality of medical care, shall be qualified for membership on the Medical Staff.” (Italics added.)
Article VIII, section 4 of the bylaws governs the time, grounds, and nature of appellate review by the board. Subsection d. thereof provides: “d. Nature of Appellate Review. The proceedings by the Board of Trustees shall be in the nature of an appellate hearing based upon the record of the hearing before the judicial review committee, provided that the governing body may, in its discretion, accept additional oral or written evidence subject to the same rights of cross-examination or confrontation provided at the judicial review committee hearing. Each party shall have the right to present a written statement in support of his position on appeal, and in its sole discretion, the Board of Trustees may allow each party or representative to personally appear and make oral argument. At the conclusion of oral argument, if allowed, the Board of Trustees may thereupon at a time convenient to itself conduct deliberations outside the presence of the appellant and respondent and their representatives. The Board of Trustees may affirm, modify or reverse the decision of the judicial review committee, or, in its discretion, refer the matter for further review and recommendation.”
The second letter is not included in the record before us. Discussion occurring at the appellate review hearing, however, provides a clear indication of its contents.
As indicated above, plaintiff had been advised that the medical executive committee had denied his application “on the basis of recommendations received from references *623furnished by you in your letter....” He had also been advised by a subsequent letter furnishing him with a compilation of the references’ responses that “[t]he Medical Executive Committee based its decision upon these recommendations.”
The letter closed on the following note: “Problems in our Valley started five years ago with the additional [i/c] of Eisenhower Medical Center. As you will recall, in order to attempt to justify the need for those additional beds in our community, the millionaires who supported that project strictly as a tax gimmick, subscribed to Stanford University to perform a research project to establish the need for beds here. To their dismay, and as most of us already knew, the report stated frankly that there was no need for additional beds in our community, and advised those individuals to look to other geographic areas if they truly wanted to supply needed community medical services. Nevertheless, Medical Center was constructed, due to political and regional influence, and the quality and organization of medical care in our community was badly disrupted....There is no rhyme or reason to adding a single hospital bed in the Coachella Valley, and only because of the deliberate distortion, secret agreements and misrepresentations on which your original decisions were based, have those selfish powers proceeded thus far.”
PlaintifFs failure to file a replication to the answer requires that all ultimate facts contained therein be accepted as true unless countervailed by proof. (See Hunt v. May- or & Council of Riverside (1948) 31 Cal.2d 619, 623 [191 P.2d 426]; Most v. First Nat. Bank of San Diego (1966) 246 Cal.App.2d 425, 432 [54 Cal.Rptr. 669].) The answer’s allegations concerning prejudice, however, were largely conclusory in nature and in any event were met by material in the administrative record.
The application form specifically reflects the action taken upon it in 1972 and 1974, and its inclusion in the record at defendant’s instance would indicate in the absence of any other similar form in the record that it was also utilized in the processing of the 1975 application.
The trial court found as a fact that defendant hospital “has facilities for surgery, complete laboratory, nuclear medicine, radiology and angiography, together with other facilities, and a continuing education program for its staff.” It is alleged by plaintiff, and denied by defendant for lack of information or belief, that defendant “is the only hospital in the area” that possesses a number of these facilities; the trial court made no finding on this point. As we have recently pointed out, however, “the application of the common law rule does not depend on the existence of ‘monopoly’ power.... The judicial inquiry, rather, has consistently been focused on the practical power of the entity in question to affect substantially an important economic interest.” (Ezekial v. Winkley (1977) 20 Cal.3d 267, 277 [142 Cal.Rptr. 418, 572 P.2d 32].)
In so concluding, of course, we by no means declare that, in the words of the dissenting opinion, “rules for staff admission applicable to public hospitals apply equally to private hospitals.” (Dis. opn., post, at p. 636.) We note that the opinion, while purporting to quarrel with the rule which we do state, adopts as its own a Court of Appeal opinion which explicitly declares that “standards for admission to staff privileges may not be ‘so vague and ambiguous as to provide a substantial danger of arbitrary discrimination in their application’” (dis. opn., post, p. 638, italics added)—and then proceeds to apply that rare standard to the very case before us.
The bylaw in Rosner permitted exclusion based upon a determination of the applicant’s “‘characteristics of cooperation, apparent ability to get along with others, and general qualifications of personality which would insure in the opinion of the [credentials] committee, that the applicant would be temperamentally and psychologically suited for cooperative staff hospital functions with other members of the Medical Staff and with other hospital personnel.’” (58 Cal.2d at p. 596.)
The hospital involved in Rosner was one maintained by a local hospital district and as such was governed by the provisions of The Local Hospital District Law. (Health & Saf. Code, § 32000 et seq.) Although our decision contains language applicable to eligibility standards in general, our narrow holding was that the standards for eligibility in district hospitals were those set forth in Health and Safety Code section 32128, which as then constituted looked only to competence and made no reference to general suitability for hospital practice as a condition of eligibility. Section 32128 has since been amended to provide that the rules of a district hospital shall include “2. Provision for procedure for appointment and reappointment of medical staff as provided by the standards of the Joint Committee [.r/c] on Accreditation of Hospitals.”
The model bylaws of the Joint Commission on Accreditation of Hospitals, of which we take judicial notice (Evid. Code, § 452, subd. (h)), contain a staff eligibility provision which is substantially identical to the one we here consider. (See Joint Commission on Accreditation of Hospitals, Guidelines for Formulation of Medical Staff Bylaws, Rules and Regulations (1971) art. Ill, § 2(a), p. 7.) (See generally Anton v. San Antonio Community Hosp. (1977) 19 Cal.3d 802, 818-820 [140 Cal.Rptr. 442, 567 P.2d 1162].)
“[I]n the modern hospital, staff members are frequently required to work together or in teams, and a member who, because of personality or otherwise, is incapable of getting along, could severely hinder the effective treatment of patients.” (Huffaker v. Bailey, supra, 273 Ore. 273, 278, italics added.)
“The absence of a compatible team working together could impair the doctor’s performance and consequently undermine the effectiveness of the treatment given the patient.” (Silver v. Castle Memorial Hosp. (1972) 53 Hawaii 475, 479 [497 P.2d 564], fn. omitted, italics added.)
The Supreme Court of Hawaii, we note, in a case heavily relied upon by defendant itself, has stated a similar view: “It has been pointed out that ‘considerations of team spirit and cooperativeness can be as important as technical skill in recommendations for staff appointments; or, put another way, professional competence in hospital practice should, according to modern hospital theory, include qualities needed for cooperative staff work.’ Note, Hospital Staff Privileges: The Need for Legislation, 17 Stan. L.Rev. 900, 905 (1965). The requirement that a doctor have a cooperative personality does not mean, however, that exclusion by a hospital board will be upheld for other than meritorious reasons. In this respect it has been held that ‘[a] denial of a physician’s application upon the basis that his appointment will cause disharmony among the medical staff must be clearly and persuasively supported by the record. The record should also clearly and persuasively indicate that such prospective disharmony probably will have an adverse effect on patient care and not merely annoy or displease certain physicians and administrators' [Citation.]” (Silver v. Castle Memorial Hosp., supra, 53 Hawaii 475, 479, fn. 4, italics added.)
The following inquiries—posed by members of the two deliberative bodies at their respective hearings—are representative: “Cone [judicial review committee member]: Under qualifications for membership, under Section 2, Article III, there is a statement about ability to work with others and I think that is coming into question at this point. This controversial attitude that has been mentioned on several occasions and in these recommendations and that is somewhat disturbing to me, because I can’t get a handle on it, I don’t know what that is supposed to mean. I don’t understand that and I think *631it is a fundamental point and we need this explanation and I hoped you would be able to provide us with it.”
“Simon [appellate review committee member]: Counselor, I’m getting lost here and I want to ask a question. Each time Dr. Miller asks this question he always refers to how they get along with patient care, his counsel asks questions of how they get along with other doctors, now which, where are we? Are we on his ability to get along with other doctors or are we on his ability to get along with other doctors concerning patient care? I’m getting lost in the shuffle and there’s lots of words.”
The medical executive committee did attempt at one point to establish through testimony that inability to “get along” with other doctors had an inherently adverse effect upon the level of patient care:
“Mour [attorney for medical executive committee]: May I ask one question. Dr. Tarleton, looking at the ability to get along in the entire hospital milieu of efficient working of committees, and efficient working of the staff which all bears on the patient care, would you agree with that, that the ability to get along in these staff meetings and with your fellow physicians, whether or not it’s a one to one relationship regarding a patient, is important in the overall quality of patient care?
“Tarleton [witness]: I would agree to that statement.
“Mour: And would you agree that if you have a physician who is disliked by a reasonably large number of his fellow physicians that it will interfere with that ability to get along and render that type of quality patient care?
“Tarleton: I would agree.
“Mour: Do you think that Dr. Miller’s reputation in the community is such that regardless of the one to one relationship in a particular case that you might have had that you believe that his general reputation or inability to get along or work with others would impair that ability in the hospital to render effective patient care or impair the quality of patient care?
“Tarleton: I understand your statement I would say yes. I think Dr. Miller’s inability to get along with people has proven itself numerous times.... ”