dissenting:
I respectfully dissent. I would hold that equitable estoppel ordinarily does not apply to cases where an unwed custodial parent seeks back child support from a noncustodial parent. In the alternative, if equitable estop-pel does apply, I would find that the trial court’s findings of fact do not support the *683conclusion that the requirements of equitable estoppel have been met. Therefore, I would reverse.
The majority goes to great lengths to characterize Parker’s claim as “reimbursement of child-rearing expenses” in order to find that the doctrine of equitable estoppel applies. It does so to avoid the consequences of our prior case law, which clearly states, “The right to support from the parents belongs to the minor children and is not subject to being bartered away, extinguished, estopped or in any way defeated by the agreement or conduct of the parents.” Hills v. Hills, 638 P.2d 516, 517 (Utah 1981) (citations omitted). It is clear to me that what Parker is claiming is back child support, as contemplated by section 78-45a-3 of the Utah Code. That section provides that when a delayed paternity action is filed, “[t]he father’s liabilities for past education and necessary support are limited to a period of four years next preceding the commencement of an action.” Utah Code Ann. § 78-15a-3 (emphasis added). The monies sought here are clearly within this definition. The majority’s characterization of Parker’s claim as “reimbursement to a parent ... of monies already expended in support of children who ... were well eared for and not left in need” is a convenient fiction. The statute certainly cannot have assumed that the only monies recoverable were those never spent to support or educate the minor.
Utah’s child support laws and the guidelines that accompany them are designed to maximize support to children from both parents. See Utah Code Ann. § 78-45-3(1) (“Every father shall support his child ....”); id. § 78-45-4(1) (“Every woman shall support her child_”). Utah’s clear policy is to require both parents to support their child to the extent that each is financially able. To that end, Utah’s child support guidelines provide a worksheet on which a calculation is made that essentially compares the relative income and obligations of each parent. See Utah Code Ann. § 78-45-7.7. The worksheet takes these figures and specifies an overall amount of support to be provided to the child, based on the combined income of both parents. See id. The worksheet then calculates the relative amount of support due to the child from each parent, in proportion to each parent’s income. See id. The fact that the noncustodial parent, in many cases the father, then pays to the custodial parent his share of the child’s support in no way diminishes the fact that the custodial parent is also required to pay her share of the child’s support. In effect, the majority holds that because the mother met her part of the obligation (and that part turned out to be sufficient to prevent the children from requiring public assistance), the father has been absolved of his responsibility to the child and now simply owes a debt to the mother.
Such an argument ignores the reality that a single parent supporting a child almost certainly will provide a lesser level of support than would have been the ease if the other parent had paid his or her share. The money that the noncustodial parent was required by law to provide will not simply materialize in the custodial parent’s bank account to be spent on the children and reimbursed from the noncustodial parent at some point in the future. In reality, the children will simply go without that support. By the majority’s reasoning, any support sufficient to keep a child out of “need,” which apparently means off of welfare, is definitionally adequate and all to which the child is entitled. This result seems not only unrealistic but contrary to Utah law. First, if anything above the welfare level was adequate, the legislature would not have required support guidelines based on the parents’ incomes; we would have a flat per child fee that provides the same level of support regardless of parental income. As Justice Durham emphasizes in her separate dissent, child support is designed not solely to keep children off of welfare, but to support them at the level to which their parents’ financial capacities entitle them. I agree with Justice Durham’s statement that when one parent does not provide his or her share of support, in most instances the child’s standard of living simply falls.
In toto, Parker’s claim is properly characterized as one for past support of the twins, not one for reimbursement. Thus, I would hold that equitable estoppel does not apply for claims of back child support, unless record evidence can show that the support that *684should have been provided by one parent was indeed provided by the other parent and that therefore the claim should truly be labeled one of “reimbursement.” In the more usual application, where the children have simply done without the noncustodial parent’s support, estoppel should have no application.
In the alternative, if, as the majority holds, estoppel does apply in such situations, I would hold that in this instance, the elements of estoppel have not been met. I begin with a discussion of the standard of review. Here, three aspects of the standard of review are relevant. First, as to the factual findings made by the trial court, I am constrained by the standard that provides, “[W]e will not reverse the findings of fact of a trial court sitting without a jury unless they are ‘against the clear weight of the evidence, thus making them clearly erroneous.’ ” MacKay v. Hardy, 896 P.2d 626, 629 (Utah 1995) (quoting In re Estate of Bartell, 776 P.2d 885, 886 (Utah 1989) (additional internal quotation omitted)). In this case, the parties do not challenge the trial court’s factual findings. Therefore, we are bound by them.
Second, whether the trial court correctly concluded that those found facts' constituted equitable estoppel is “an issue of law.” Western Kane County Special Serv. Dist. No. 1 v. Jackson Cattle Co., 744 P.2d 1376, 1377 (Utah 1987). As we have noted, however, this determination begins, rather than ends, the inquiry into the amount of discretion we should give to a trial court to conclude that the facts constitute equitable estoppel. See State v. Pena, 869 P.2d 932, 937 (Utah 1994).
Third, having determined that this case presents an issue of the application of a stated general principle of law to specific facts, I must address the question of how closely we will scrutinize the trial court’s “determination of whether a given set of facts comes within the reach of a given rule of law.” Id. at 936. Trial courts are given differing degrees of discretion in making rulings on this sort of mixed question of fact and law, depending on several considerations. Id. at 938-39. It is this third question that most concerns me today.
Based upon the facts outlined by the majority, the trial court ruled that there was sufficient evidence to establish the elements of equitable estoppel. We have previously stated the elements of the general doctrine of equitable estoppel:
Estoppel is an equitable defense that requires proof of three elements: (i) a statement, admission, act, or failure to act by one party inconsistent with a claim later asserted; (ii) reasonable action or inaction by the other party taken or not taken on the basis of the first party’s statement, admission, act, or failure to act; and (iii) injury to the second party that would result from allowing the first party to contradict or repudiate such statement, admission, act, or failure to act.
CECO Corp. v. Concrete Specialists, Inc., 772 P.2d 967, 969-70 (Utah 1989) (citing Celebrity Club, Inc. v. Utah Liquor Control Comm’n, 602 P.2d 689, 694 (Utah 1979)). The trial court appears to have had in mind the proper general legal principles. It made findings as to each of these three elements. Therefore, I have no basis for concluding that the trial court did not apply a correct statement of the general law. Further, the trial court’s findings of fact, which it used to support its ultimate conclusion that Parker was estopped from claiming back child support, though not uncontroverted, were not wholly lacking support in the evidence. Specifically, the court found that (i) Parker made no calls and wrote no letters to Irizarry asking for support; (ii) Parker left Irizarry’s name off the children’s birth certificates; (iii) Parker had the support and financial assistance of her family, and her family was discouraging her relationship with Irizarry; and (iv) Irizarry was willing to support the children, but Parker refused such support. These findings led the trial court to conclude that Parker
made statements, took actions that led [Iri-zarry] to reasonably conclude that [Parker] wanted nothing to do with him and didn’t want his support. In reliance upon that, [Irizarry] got on with his life, got married[,] and started a family and under those circumstances should not be responsible for the payment of support until ... this complaint was filed.
*685I am left, then, with the question of whether the trial court correctly concluded that the facts it found are sufficient to support the legal conclusion that equitable estoppel has been established. More specifically, in the context of an effort by the unwed father of a child to avoid a legal child support obligation to the unwed mother, all for the benefit of the child, were the statements and acts of the mother sufficiently clear to support the legal conclusion that they were “inconsistent with a claim later asserted” for child support? I would conclude as a matter of law that they were not.
It is important to state that as a general matter, the mixed question of whether the requirements of the law of estoppel have been satisfied in any given factual situation is one that we review by granting the trial court a fair degree of discretion. Equitable estoppel is a doctrine that is simply stated, yet its principles apply across a wide variety of factual and legal situations. The sheer variety of circumstances argues strongly that we should not lightly substitute our judgment for that of the trial courts. Pena, 869 P.2d at 939. That does not, however, mean that we will always defer. There are times when we must expand or contract or more closely define the pasture within which the trial courts may roam in the exercise of that discretion: this is one such situation.
We have traditionally granted considerable discretion to trial .courts engaged in child support determinations. See Hunter v. Hunter, 669 P.2d 430, 431 (Utah 1983). In Pena, however, we discussed the various considerations underlying our decision to grant a trial court discretion in determining “the legal consequences of facts.” 869 P.2d at 937, 939. One reason to narrow the “pasture” in a particular factual context is the need to vindicate important public policies. Id. at 938. In the situation where an unmarried mother seeks back child support, the important public policy, discussed above, that favors ensuring that parents provide support to their children requires that we narrow the pasture in which a trial court may roam in determining whether the claimant is es-topped from asserting a claim.
In the murky factual context of the rejection of an unwed father by an unwed mother, where a too-casual finding of estoppel would operate to relieve an unwed father of his legal obligation to support his child, in contradiction of public policy, I find it necessary to narrow the trial court's pasture. Utah’s public policy should not permit a rejection of the unwed father to be lightly construed as a rejection of his legal obligation to support the child even absent any ongoing contact with the mother or child, which are separate legal issues. Therefore, for the trial court to find the first element of estoppel — “a statement, admission, act, or failure to act by one party inconsistent with a claim later asserted” — I would hold that the mother’s statements must approach an explicit and unequivocal rejection of legally due support obligations. A finding that the element is proven by statements that could be interpreted as rejecting an ongoing personal relationship with the father should not be sustained on appeal.
In this case, the trial court found that Parker made three statements to Irizarry, all before the birth of the twins, and once telephoned Irizarry to announce the twins’ birth. The prebirth statements were to the effect that Parker did not want Irizarry’s money, that she wanted nothing to do with him, that she would take care of herself, and that she intended to name the children “Parker.” The occasions on which she made these statements were all before the children were born, during the time when she and Irizarry were working out their relationship and she was dealing with the ongoing challenges of pregnancy and an uncertain future. These statements are not clear enough to be inconsistent with a later claim for past support. Even the most damaging statement Parker made, that she did not want Irizarry’s money, is ambiguous at best. It could have referred to pregnancy and childbirth expenses just as easily as future child support.
I am unable to say that the words Parker uttered were clearly a rejection of Irizarry’s legally obligated support for the children, as opposed to a rejection of any ongoing personal relationship with Irizarry. Therefore, these facts should not support a finding that *686the first element of estoppel is met. The trial court’s finding of estoppel should fall.
In finding that the facts are sufficient to find estoppel, the majority places great importance on Irizarry’s claim that he relied on Parker’s statements, going on to marry and have children, incurring financial obligations that he would not have incurred had he known of his obligation to support the children. This argument should fail. First, this seems an unrealistic assumption. There is no proof Irizarry would otherwise have put his personal life on hold simply because he might someday have to pay child support. A more logical inference is that he went on to marry because he understood that the mother of his twins had no interest in a relationship with him. This inference is strengthened by the fact that, well after this action was filed, he continued to increase his own financial obligations, having a fourth child with his wife, Patricia, with full knowledge that his obligations to the twins were at issue before the courts. I certainly do not suggest that Irizarry was not entitled to do so, but these actions undermine his claim that he would not have gone on with his life, married, and had children had he known that Parker would look to enforce his obligation to provide support to the twins. As we stated in Baggs v. Anderson, 528 P.2d 141 (Utah 1974), the reliance requirement “is not satisfied by the mere fact that he indulged in the pleasant and euphoric assumption that he would not have to meet his obligations and that he bought a more expensive car and moved to a more expensive apartment.” Id. at 144.
Second, beyond the unreasonableness of the inference the majority draws from Irizar-ry’s conduct, the fact is his uncontroverted testimony shows he did not rely on Parker’s statements as freeing him from his obligation. He stated that even after she said that she did not want anything to do with him, did not want his money, and would take care of herself, he believed that he was still financially responsible for his children. At that time, he stood ready to support the children had it been required of him.
Third, Irizarry’s claim of estoppel ultimately rests on the conclusion that it was reasonable for him to rely on Parker’s statements and actions as indicating that she would not seek child support from him. In light of the discussion above regarding the ambiguity of Parker’s statements, and in light of Utah’s law on the importance of child support, it would not be reasonable for Iri-zarry to rely on Parker’s statements as freeing him from his support obligation. Utah law provides, “The right to support from the parents belongs to the minor children and is not subject to being bartered away, extinguished, estopped or in any way defeated by the agreement or conduct of the parents.” Hills, 638 P.2d at 517. That, under facts not present here, equitable estoppel might be applied to prevent a parent from claiming past child support does not negate the fact that a custodial parent cannot affect a child’s right to future support from that child’s other parent. Because Parker could not waive the twins’ right to support, Irizarry could not have been entitled to assume that he would never be required to support his children.
And finally, because the law also provides for collection of past child support for four years prior to a paternity action, Utah Code Ann. § 78-45a-3, the most Irizarry could have relied upon was that he would not be required to support his children for more than four years prior to the time Parker filed a paternity action against him.
I emphasize that I am not here substituting my judgment for that of the trial court, nor would I signal an intent to closely scrutinize factual findings of estoppel in general. I would simply hold that in situations where an unwed pregnant woman may initially be unenthusiastic about continuing a personal relationship with the father, her statements must clearly reject money for the support of the child before she can be held estopped from collecting such support. There needs to be some specific indication that the mother is rejecting the legally due child support, not just contact by the father and general indications of support from the father, before we should permit a finding of estoppel. In the metaphor of Pena, I would not leave trial judges a small pasture. I would fence off only a factual corner of that pasture because of the strong public policies implicated by our declining to do so.
*687I would reverse the court of appeals and remand to the trial court for further proceedings consistent with this opinion.
DURHAM, J., concurs in Chief Justice ZIMMERMAN’S dissenting opinion.