Following a public hearing pursuant to § 168.118, RSMo 1978, Mary Ellen Kimble, a “permanent teacher”, was found by The Worth County R-III Board of Education to have engaged in “immoral conduct” (§ 168.114.1(2), RSMo 1978), and her indefinite contract was terminated. An appeal was taken to the Circuit Court of Worth County which reversed the decision of The Worth County R-III Board of Education (hereinafter Board) and ordered that Mary Ellen Kimble (hereinafter Kimble) be reinstated, returned to permanent teacher status, and entitled to compensation for the period suspended from work.
The matter reaches this court on an appeal by the Board from the judgment entered by the Circuit Court of Worth County. The circuit court reversed the decision of the Board on the grounds that it “was arbitrary, capricious and unreasonable”, constituted “an abuse of discretion”, and “was unsupported by competent and substantial evidence upon the whole record.” The circuit court further held “that there was not competent and substantial evidence upon the whole record ... that the alleged ‘immoral conduct’ rendered the teacher unfit to teach or that the teacher’s teaching ability was adversely affected in any way.” Parenthetically, the judgment of the circuit court evaporates insofar as having any bearing on judicial review at the appellate level due to strictures imposed thereon in contested administrative cases, infra.
Section 168.120(2), RSMo 1978, provides that an appeal from the decision of the Board shall be governed by the provisions of Chapter 536. In terms of administrative review this was a contested case (§ 536.-010(2), RSMo 1978) and therefore the scope of review for both this court and the circuit court is statutorily prescribed by § 536.140, RSMo 1978.1
Review of contested administrative cases has been judicially addressed on numerous occasions. Reference is made to the following cases in the context of the instant appeal. Neither the circuit court nor this court reviews the decision of the Board de novo. Michler v. Krey Packing Co., 363 Mo. 707, 253 S.W.2d 136, 141 (banc 1952). This court does not review the decision of the circuit court; to the contrary, each reviews the decision of the Board. Edmonds v. McNeal, 596 S.W.2d 403, 407 (Mo. banc 1980). Although all evidence before the Board is considered on judicial review, both the circuit court and this court are precluded from substituting their judg*952ment on the evidence and neither may set aside the Board’s decision unless it is unsupported by competent and substantial evidence on the whole record or is otherwise invalid. Harrod v. Board of Education, 500 S.W.2d 1, 6 (Mo.App.1973). The evidence must be considered in the light most favorable to the Board’s decision, together with all reasonable inferences which support it. Id. Determination of the credibility of witnesses is a function of the Board and entitled to deference on judicial review. Merideth v. Board of Education, 513 S.W.2d 740, 745 (Mo.App.1974). If evidence before the Board warranted either of two decisions, the Board’s decision is binding on judicial review, and it is irrelevant that there may be supportive evidence of an opposing view. Hanebrink v. Parker, 506 S.W.2d 455, 458 (Mo.App.1974). Inclusion within the scope of judicial review of contested cases that the administrative decision must be supported by competent and substantial evidence on the whole record (§ 536.140.2(3), RSMo 1978), is rooted in Art. V, § 18, Constitution of Missouri (as amended 1976). By reason of its constitutional heritage, determination of whether an administrative decision in a contested case is supported by competent and substantial evidence on the whole record is of magnum importance.
The Board relies on one point on appeal, namely, its decision was supported by competent and substantial evidence on the whole record when reviewed in accordance with attendant judicial guidelines addressing the scope of judicial review. Kimble counters the Board’s position on a variety of grounds. One, the Board’s decision was not supported by competent and substantial evidence on the whole record. Two, “immoral conduct” as prescribed by § 168.-114.1(2), supra, is unconstitutionally vague in violation of Amendments V and XIV of the Constitution of the United States and Art. I, § 10, of the Constitution of Missouri; moreover, the incidents relied on, in any event, did not constitute “immoral conduct”. Three, the purported instances of “immoral conduct” did not render her unfit to teach. Four, the doctrine of laches barred two of the three incidents found by the Board to constitute “immoral conduct.” All of the aforementioned grounds were raised by Kimble before the Board and reasserted in her petition for review in the circuit court.
The charge levelled against Kimble which culminated in termination of her indefinite contract by the Board was predicated upon three instances of alleged “immoral conduct” within the ambit of § 168.-114.1(2), supra. The three incidents constituting “immoral conduct”, supra, were as follows: that during the 1973-74 school year a teapot which was a prop in a school play was returned by Kimble after word was disseminated that it was missing; that during the 1976-77 school year she took $20 from gate receipts collected at a basketball game, although she refunded the money after being confronted about the matter; and that in February, 1982 she took a set of books belonging to the school district, indicated that they had never been received from the vendor when confronted about them, and then subsequently returned them to the school library. It is appropriate to note at this juncture that in a pedagogic context, Kimble served as teacher-librarian.
The Board made detailed findings of fact substantiating all three incidents set forth in the charge as constituting “immoral conduct”, and, additionally, that her conduct with respect thereto “required extra precautionary measures to supervise her”, “had a negative effect on the student relationship and teacher relationship existing in The Worth County R-III School District”, and that continuance of her employment “creates additional administrative and supervisory burdens as well as distrust among the staff and faculty and has an adverse and detrimental effect on the students, faculty and the educational process of The Worth County R-III School District.”
*953As frequently occurs in contested eases, a close perusal of the instant record in toto reveals its share of contradictory evidence, conflicting inferences, and divergent theories. Be that as it may, when the whole record is considered in light of the attendant principles governing the scope of judicial review of contested administrative cases, the conclusion is inescapable that the findings and decision of the Board were supported by competent and substantial evidence on the whole record and do not reflect that the Board abused its discretion or acted in an arbitrary, capricious or unreasonable manner. Any natural impulse for reviewing courts to substitute their judgment on the evidence for that of the administrative tribunal in contested cases has a momentum of its own which must be held in check.
Attention now focuses on whether the Board’s decision was otherwise invalid by reason of any of the other infirmities attributed to it by Kimble. Her contention that the statutory basis (§ 168.114.1(2), supra) upon which the Board’s decision necessarily rested was “unconstitutionally vague”, thereby rendering it invalid, is laid to rest in Ross v. Robb, 662 S.W.2d 257, 259 (Mo. banc 1983):
“In Thompson v. Southwest School District et al., 483 F.Supp. 1170 (W.D.Mo.1980), the plaintiff, a teacher dismissed from service for engaging in ‘immoral conduct,’ alleged that section 168.-114.1(2), RSMo 1978, was impermissibly vague and denied her due process of law. The court agreed that, in the abstract, the phrase ‘immoral conduct’ was constitutionally suspect under the strict standards of construction to be employed in criminal and first amendment contexts. Id. at 1179. The court went on to say, however, that the phrase was part of a statutory scheme; that, construed with the other subsections of the statute, the phrase is ‘capable of being given a more precise judicial construction so as to avoid the vagueness issue.’ Id. at 1180. The court concluded that immoral conduct relates to conduct rendering a teacher unfit for the performance of his duties. Id. More precisely, the court found that immoral conduct means ‘conduct rendering plaintiff unfit to teach.’ Id. at 1181. This analysis persuades denial of Ross’s constitutional challenge.” (emphasis added)
The foregoing logically brings this court to Kimble’s bifurcated argument that the incidents relied on did not constitute “immoral conduct”, and, even if subject to being so construed, failed to render her unfit to teach. This argument is soundly refuted by competent and substantial evidence permeating the whole record supporting both the conduct alleged and the fact that such rendered her unfit to teach, thus meeting the test of “immoral conduct” set forth in Ross v. Robb, supra. The taking of property belonging to another without consent, notwithstanding its return when confronted with such wrongdoing, breaches even the most relaxed standards of acceptable human behavior, particularly so with regard to those who occupy positions which bring them in close, daily contact with young persons of an impressionable age. It is eminently proper to note that Kimble, in addition to her duties as librarian, taught “library” and “reference” skills at the elementary level on a regular basis, and on an incidental basis at the high school level.
Failure to invoke separate charges when each of the first two incidents occurred does not unequivocally suggest they were considered de minimis or condoned, and any attempt to do so places them in a false perspective. All three incidents were relied on to show a continuing pattern of behavior which crested when the final incident occurred in February of 1982 immediately following which charges were lodged resulting in termination of Kimble’s indefinite contract. Any argument that reliance upon the first two incidents was indicative of an arbitrary, capricious and unreason*954able attitude on the part of the Board is negated when all the incidents are collectively viewed as evidencing a pattern of continuing behavior.
Kimble’s final contention, that the first two incidents relied upon should have been barred by the doctrine of laches, and failure to so treat them tainted the Board’s decision with incurable prejudice, is unpersuasive. Admittedly, the first of said incidents occurred during the 1973-74 school year and the second occurred during the 1976-77 school year.
Assuming, arguendo, that the doctrine of laches is applicable in contested cases before administrative tribunals, reference is had to its salient principles. There is no fixed period within which a right or claim must be asserted in order that it avoid being barred by laches; temporal limits are drawn in light of the circumstances of the particular case; mere delay, in and of itself, does not constitute laches; laches is a question of fact to be determined from all the evidence and circumstances adduced at trial; laches cannot be invoked to thwart right or justice, but only to defeat resultant prejudice, if not invoked, to one asserting it; and he who asserts laches carries the burden of proof. Metropolitan St. Louis Sewer District v. Zykan, 495 S.W.2d 643, 656-57 (Mo.1973).
Prejudice which supports laches generally falls into one or the other of two categories, i.e., (1) loss of evidence which would support the position of one seeking to invoke laches with regard to the claim he is called upon to defend against, and (2) a change of position by one seeking to invoke laches in a way that would not have occurred but for the delay. Rich v. Class, 643 S.W.2d 872, 877 (Mo.App.1982).
Kimble does not claim that she was prejudiced by a change of position on her part due to delay in filing charges against her regarding the first two incidents. In terms of prejudice in its broadest sense, any delay is susceptible of the inference that the Board did not precipitously file separate charges on each of the first two incidents, but out of deference to Kimble abstained from doing so until a continuing pattern of behavior was evinced.
Kimble raises her claim of prejudice in an evidential context. Prejudice in an evidential frame of reference contemplates a loss of demonstrative evidence or the unavailability of witnesses which or who could support the position of one seeking to invoke the doctrine of laches. Powell v. Zuckert, 366 F.2d 634, 638 (D.C.Cir.1966). The burden of proof thereon rested on Kimble, which she failed to sustain. She neither asserted nor attempted to prove the loss of any demonstrative evidence which would have aided or benefited her. She neither asserted nor attempted to prove that any witnesses were unavailable who could have aided or benefited her. As a matter of fact all persons who were privy to the two incidents which she claims should have been barred by laches testified at the hearing. Moreover, the separate components which come into play in determining applicability vel non of the doctrine of laches must be balanced in each case by weighting each component in accordance with the particular facts and circumstances presented. When such is done in the instant case the scales tip in favor of rejecting application of the doctrine of laches.
Cases involving termination of tenured teachers frequently project an aura of ambivalence, thereby giving indelible substance to the admonitory principle that courts sitting in judicial review should not substitute their judgment on the evidence in lieu of that of the decisional administrative body. The scope of judicial review of administrative decisions in contested cases is sharply etched and commands compliance in order to protect against unwarranted judicial excursions into matters exclusively within the province of the appropriate administrative tribunal. See Phipps v. School District, 645 S.W.2d 91, 95-96 (Mo.App.1982).
*955On the basis of what has heretofore been said, this court holds that the decision and order of The Worth County R-III Board of Education should be, and hereby is, affirmed. Accordingly, the judgment of the Circuit Court of Worth County is reversed and the cause remanded with directions to the Circuit Court of Worth County to enter judgment affirming the decision and order of The Worth County R-III Board of Education.
Judgment reversed and cause remanded with directions.
LOWENSTEIN, J., concurs in opinion of SOMERVILLE, P.J. NUGENT, J., concurs in separate concurring opinion.. Section 536.140, RSMo 1978, insofar as here pertinent, reads as follows:
"1. The court shall hear the case without a jury and, except as otherwise provided in subsection 4, shall hear it upon the petition and record filed as aforesaid.
2. The inquiry may extend to a determination of whether the action of the agency
(1) Is in violation of constitutional provisions;
(2) Is in excess of the statutory authority or jurisdiction of the agency;
es) Is unsupported by competent and substantial evidence upon the whole record;
(4) Is for any other reason, unauthorized by law;
(5) Is made upon unlawful procedure or without a fair trial;
(6) Is arbitrary, capricious or unreasonable;
(7) Involves an abuse of discretion...."