T1 The issues before this Court are: (1) whether the district court erred in refusing grandparent's request to enforce a consent visitation order, (2) whether the district erred in treating mother's motion to terminate visitation as an objection to request for enforcement of grandparental visitation, (3) what are the standards for terminating or modifying a consent decree granting grand-parental visitation, and (4) who should bear the burden of proof in modification proceedings.
I. FACTS
T2 Laine Christian Ingram (Child) was born on May 12, 1995, to Holly Suzanne Ingram (Mother) and John Michael Knippers (Father). The parents never married and live in separate households. Mother filed a petition against Father seeking custody and child support. On December 2, 1997, the district court awarded custody of Child to Mother, set a visitation schedule for Father, and fixed the Father's monthly child support obligation.
13 On June 2, 2000, Child's paternal grandfather, John C. Knippers (Grandfather), filed a motion to intervene and for visitation. - Grandfather alleged that he had been involved in Child's life since birth, that he had provided financial and other support for both Child and Mother, that grandparen-tal visitation would be in Child's best interest, and that Grandfather had unsuccessful attempted to effect visitation through his direct contact with Mother.
4 Pursuant to an agreement, the district court entered an order on November 29, 2000, allowing visitation between Child and Grandfather. The schedule covered October and November of 2000. The parties agreed and the court ordered that further visitation would be as recommended by Child's counselor.
5 In December of 2000, Mother unilaterally terminated Grandfather's visitation with Child. Mother did not seek court approval before terminating the visitation. Grandfather filed a motion to enforce his visitation rights, alleging that Mother had unreasonably interfered and denied him visitation. He requested an order setting a specific visitation schedule, requiring Mother to post a bond, and awarding him costs and attorney fees.
T6 Mother then filed a motion seeking to terminate Grandfather's visitation. She argued that courts may not order grandparen-tal visitation absent a showing that the custodial parent is unfit or that the child will suffer harm if the visitation is not allowed. She did not allege that termination of Grandparent's visitation was in Child's best interest. Even though Mother specifically requested that the visitation be terminated and that Grandfather's motion be denied, the district court treated Mother's motion only as an objection to Grandfather's motion to enforce visitation. Grandfather then filed an application for a contempt citation for Mother's - unilateral - action - terminating Grandfather's visitation in contravention of the November 20, 2000 order. He requested reinstatement of the order, Mother's incarceration, and an award of costs and attorney fees.
T7 At a hearing on the motions, the district court placed the burden of proof on Grandfather to show Mother's unfitness or potential harm to Child. Grandfather presented the testimony of Child's counselor that termination of grandparental visitation would result in harm to Child. Mother did not allege or present any evidence that there had been a substantial change of cireum-stances or that terminating visitation would be. in Child's best interest. On April 30, 2001, the district court entered an order denying Grandfather's motion to enforce his visitation, effectively terminating Grandfather's visitation and mooting the remaining issues.
*2018 Grandfather appealed. Mother has not submitted an appellate brief even though she was given opportunity to do so. Only Grandfather's brief was before the Court of Civil Appeals and is before this Court. The Court of Civil Appeals concluded that this Court's opinion in Scott v. Scott, 2001 OK 9, 19 P.3d 273, controlled. Rejecting the district court's reliance on Neal v. Lee, 2000 OK 90, 14 P.3d 547, and In re Herbst, 1998 OK 100, 971 P.2d 395, the Court of Civil Appeals found that the controlling factor of the present case was the procedural posture which was akin to that in Scott.
19 Mother petitioned for certiorari. This Court granted certiorari and now clarifies the standard and burden of proof necessary in proceedings to enforce agreed court-ordered grandparental visitation and to clarify the standard and burden of proof required to modify a grandparental visitation order. We do not address a scenario where a grandparent is attempting to expand visitation beyond what was agreed to by a parent. These facts are not before this Court.
II. HERBST, SCOTT, AND NEAL
110 Title 10, section 5 of the Oklahoma Statutes allows a court to grant grandparen-tal visitation with an unmarried minor grandchild under certain cireamstances if the court deems it to be in the child's best interest. In Herbst, this Court held section 5 to be unconstitutional to the extent it permitted district courts to grant grandparental visitation over the objection of fit parents without a showing of potential harm to the child when the family is intact. This Court extended Herbst to apply when the children are living with one parent and the other parent is deceased. Neal, 2000 OK 90, 14 P.8d 547.
{11 Then in Scott, this Court held that termination of an existing grandparental visitation order based on agreement of the parties is not subject to collateral attack in a modification proceeding but that the moving party is required to show a change in circumstances adversely effecting the child's best interest such that a change in visitation would improve the child's temporal, moral and mental welfare. Scott, 2001 OK 9 at 15, 19 P.3d at 275. Unlike Neal and Herbst, the child in Scott was adopted. However, this was not a factor in this Court's decision. Adoptive parents have no lesser rights than biological and single parents. Further, the remand in Scott was based on the district's court failure to follow statutory procedures required by title 10, section 5.1
III. ENFORCEMENT AND STATUS OF AGREED GRANDPARENTAL VISITATION ORDER
{12 Mother claims: (1) the statute which allowed the initial grant of grandparental *21visitation required a showing of harm to Child or parental unfitness; (2) the Grandfather failed to meet his burden of showing harm; (8) the visitation should not have been granted, and (4) she should be allowed to unilaterally terminate the visitation. The problem with Mother's claim is that the initial visitation was a consent order entered after Mother and Grandfather had reached an agreement. Because Mother consented to the initial visitation, the order was not entered under authority of title 10, section 5, and Mother's rights were not infringed by the order. Further, visitation order is not now subject to collateral attack on the ground that title 10, section 5 is unconstitutional. '
118 Even if the grant of grandpa-rental visitation had been pursuant to title 10, section 5, the order is not subject to collateral attack on the grounds that section 5 was declared unconstitutional. A judgment based on a statute which is later declared, unconstitutional "is not void so as to be subject to collateral attack" but at most voidable and subject only to direct attack. Fitzsimmons v. City of Oklahoma City, 1942 OK 422, 18, 135 P.2d 340, 343. Applying this rule, a grant of grandparental visitation made under the authority of section 5 is "voidable and subject to direct attack, but it [is] not void so as to be subject to collateral attack." Fitzsimmons, 1942 OK 422 at 18, 135 P.2d at 343; see Scott, 2001 OK 9, 19 P.3d 273.
114 A judgment based on an agreement of "the parties is enforceable and valid even though it does what a trial court cannot [otherwise] do, provided the agreement does not contravene public policy." Whitehead v. Whitehead, 1999 OK 91, 110, 995 P.2d 1098, 1101. Nothing in title 10, section 5 or this Court's jurisprudence prevents a court from granting grandparental
visitation when the parties agree to the visitation. Mother has failed to present any convincing argument that the grandparental visitation order was void such that it is subject to collateral attack in an enforcement proceeding.
115 The Legislature has enacted procedures in title 10, section 5(E) that a district court must follow before acting on a motion to enforce grandparental visitation. Section 5(EB)(2) requires the court to direct mediation and enter an order. If the parties reach an agreement, the order shall memorialize the parties' agreement. The court may sanction the parent by assessing reasonable attorney fees, mediation costs, and court costs and ordering "any other remedy the court considers appropriate" including finding the parent in contempt of court, Okla. Stat. tit. 10, § 5(E)-(F). However, because Grandfather filed a motion for enforcement of his visitation rights, the court must follow the procedure outlined in title 10, section 5(E) requiring that the court direct the dispute to mediation and that the mediator file a record of mediation termination along with any agreement reached by the parties. Thus, Grandfather's motion to enforce should have been granted subject to the outcome of Mother's motion to terminate and the procedures set out in title 10, section 5(E).
IV. MOTION TO TERMINATE GRANDPARENTAL VISITATION
{16 The district court treated Mother's motion to terminate grandparental visitation as a response to Grandfather's motion to enforce. Because Mother not only responded to Grandfather's motion but also sought relief distinct from Grandfather's, the court should have cast Mother's motion both as a response to Grandfather's motion to *22enforce visitation and as a motion to terminate the visitation.
1 17 In Scott, 2001 OK 9, 19 P.3d 273, the mother sought to have a grandparental visitation order modified. She did not appeal the initial grant of visitation but collaterally attacked the order in the modification proceeding. The initial visitation order was entered after the biological father's rights were terminated and the stepfather had adopted the child. The case was remanded to the district court for failure to hold a hearing pursuant to title 10, section 5 of the Oklahoma Statutes. This Court reiterated that the burden was on the party seeking modification to show a change in cireumstances adversely effecting the best interest of the child such that the welfare of the child would be improved by modification of the initial order. Id. at 15, 19 P.3d at 275.
18 The "change of cireumstance" requirement is akin to the doctrine of res judicata and furthers the same policy considerations. Boatsman v. Boatsman, 1984 OK 74, 15, 697 P.2d 516, 519. The "change of circumstance" requirement accords "some degree of finality to factual and legal determinations made in [child] custody matters, which if absent would lead to constant relit-igation of matters already determined." Id. The "change of cireumstance" requirement assures that the same claims available in a previous visitation proceeding will not be subjected to continual relitigation. A consent judgment is entitled to the same preclu-sive treatment as a contested judgment. Id. Just as claim preclusion "teaches that a final judgment on the merits of an action precludes the parties from relitigating not only the adjudicated claim, but also any theories or issues that were actually decided, or could have been decided in that action," the "change of circumstances" requirement is a safeguard to prevent relitigation of issues which had been decided or could have been decided by a prior visitation order. Read v. Read, 2001 OK 87, n. 18, 57 P.3d 561, 567 n. 18.
119 Mother seeks here to litigate issues which could have been litigated in the initial proceeding. While a fit parent contesting grandparental visitation is entitled to a presumption that the parent will act in the best interest of the child, Neal, 2000 OK 90, 14 P.3d 547, a court will not modify a valid visitation order without the moving party first showing a substantial change of cireum-stances. Scott, 2001 OK 9 at 15, 19 P.3d at 275. Having agreed to the initial grant of visitation with Grandfather, Mother cannot in this subsequent proceeding litigate the issue of harm without showing a change in cireum-stances and Child's best interest will be served by terminating the visitation.
120 The district court should have considered Mother's motion as a request to terminate grandparental visitation. On remand, the district court should conduct a hearing on Mother's motion to terminate. The burden is on Mother, as the moving party, to first show a change of cireum-stances and to then show that termination of the visitation would be in Child's best interest. The district court should consider all relevant factors in determining the Child's best interest giving due regard for Mother's interest in raising her child. Mother must present evidence more than that she simply has changed her mind and does not wish Grandfather to have any contact with Child.
121 We believe our decision protects a parent's right to custody and control of a child without ignoring the child's best interest. "Having onee protected the parent's right to custody [and control of a child], at the risk of sacrificing the child's best interests, we should not then sacrifice the child's need for stability in its care and living arrangements by modifying those arrangements more readily than in a parent-parent case." C.R.B. v. C.C., 959 P.2d 375, 380 (Alaska 1998) (emphasis omitted).
V. CONCLUSION
[ 22 The district court should have considered Mother's motion as one to terminate grandparental visitation placing the burden on Mother to show a change of cireumstances and to show that a modification would be in Child's best interest. If the district court finds that there has not been a change of cireumstances or that termination is not in Child's best interest, it should consider *23Grandfather's motion to enforce visitation pursuant to the initial grant of visitation and follow the procedures set out in title 10, section 5(E). Whether or not the district court determines to continue or terminate grandparental visitation, Mother has failed to show that the initial order granting grandpa-rental visitation was void.
€ 23 The Court of Civil Appeals' opinion is vacated. The judgment of the district court is reversed, and the case is remanded for proceedings consistent with this opinion.
COURT OF CIVIL APPEALS OPINION VACATED; JUDGMENT OF DISTRICT COURT REVERSED; CAUSE REMANDED.
24 OPALA, V.C.J., HODGES, LAVENDER, HARGRAVE, SUMMERS, BOUDREAU, WINCHESTER, JJ., concur. 1 25 WATT, C.J., (Joins KAUGER, J.), KAUGER, J. (by separate writing), dissent.. The United States Supreme Court has not ad, dressed the issue presented by this appeal. Further, this Court's resolution of the issues does not contravene any of the United States Supreme Court's jurisprudence. The United States Supreme Court addressed the issue of grandparen-tal visitation in Troxel v. Granville, 530 U.S. 57, 120 S.Ct. 2054, 147 LEd.2d 49 (2000). In Trox-el, the grandparents were seeking more visitation than the parent was willing to grant. The United States Supreme Court required that at a minimum, the trial court give weight to the parent's wishes regarding visitation by a non-parent, including a grandparent, and held that there is a presumption that a parent will act in the child's best interest and that the grandparents have the burden to overcome the presumption. It should be noted in Troxel that the parent was not seeking to modify or terminate an existing visitation order as in the present case. Consistent with Troxel, this Court held that the Oklahoma Constitution requires that a grandparent seeking visitation over the objection of fit parents must show that a denial of grandparental visitation would result in potential harm to the child.
In Dodge v. Graville, 533 U.S. 945, 121 S.Ct. 2584, 150 L.Ed.2d 745 (2001), the United States Supreme Court summarily granted certiorari, vacated the judgment of the Court of Appeals of Arizona, and remanded "for further consideration in light of Troxel. _..." In Graville v. Dodge, 197 Ariz. 591, 5 P.3d 925 (Ariz.Ct.App.2000), the grandparents were seeking a contempt citation. - After a hearing, the trial court entered an order modifying the original visitation by appointing a counselor to supervise and facilitate visitation. The "review was limited to determining whether the trial court abused its discretion by modifying the visitation order through the appointment of a supervision psychologist." Id. at 929 n. 2 (emphasis added). Unlike in Gran-ville, the grandfather in the present case is not seeking new requirements be added to the original visitation order. The United States Supreme Court recently denied certiorari in two grandparental visitation cases. McGovern v. McGovern, 201 Ariz. 172, 33 P.3d 506 (Ct.App.2001), cert. denied, 536 U.S. 959, 122 S.Ct. 2663, 153 LEd.2d 837 (2002); Jackson v. Tangreen, 199 Ariz. 306, 18 P.3d 100 *21(Ct.App.2000), cert. denied, 534 U.S. 953, 122 $.C+. 351, 151 LEd.2d 265 (2001). A denial of certiorari has no precedential effect and is not a statement of law regarding the merits of the case. Hopfmann v. Connolly, 471 U.S. 459, 461, 105 S.Ct. 2106, 85 L.Ed.2d 469 (1985). "Inasmuch, therefore, as all that a denial of a petition for a writ of certioFari means is that fewer than four members of the Court thought it should be granted, this Court has rigorously insisted that such a denial carries with it no implication whatever regarding the Court's views on the merits of a case which it has declined to review." State of Maryland v. Baltimore Radio Show, Inc., 338 U.S. 912, 919, 70 S.Ct. 252, 94 L.Ed. 562 (1950) (opinion of Frankfurter, J., regarding the denial of a petition for certiorari.).