A mother who had been the primary caretaker of her two children since their birth, and who had never violated the trial court’s visitation orders, wanted to provide a better life for her children by moving with them to another state where she had relatives and where her new husband had accepted a better-paying job. Concerned that his tenuous relationship with the children would be weakened, the children’s father objected. After a hearing, the trial court ordered that custody of the children be transferred to the father in the event the mother moved. The majority holds the trial court did not abuse its discretion in so ruling. I disagree.
When it explained its ruling, the trial court said that moving the children to another state could damage the children’s relationship with their father, but the court never mentioned the potential harm to the children from losing their mother as their primary caretaker, despite undisputed evidence that this harm would be significant. The majority acknowledges that the trial court was required to consider this detriment—indeed it acknowledges “ ‘the paramount need for continuity and stability in custody arrangements’ ” (maj. opn., ante, *1102at p. 1092, italics added)—but it assumes the trial court adequately considered this point.
In a matter of this importance, involving the custody and welfare of minor children, a reviewing court should not make such a speculative assumption. When a trial court’s explanation for exercising its discretion in a particular way does not mention a critical matter that the court was bound to consider, and does not accurately state the controlling legal standard, a reviewing court cannot simply ignore these omissions. When, as here, the appellate record raises substantial doubts that the trial court applied the proper legal principles and policies that should have guided its decision, reversal is required.
I
In May 1996, Susan Poston Navarro (the mother) petitioned the superior court to dissolve her marriage to Gary LaMusga (the father) and to obtain custody of their two young children. The father requested joint legal and physical custody. Pending final determination of the custody issue, the children remained in the family home with the mother, and the father established his own separate residence. The court appointed Philip Stahl, Ph.D., a psychologist, to conduct a custody evaluation. Pending this evaluation, the parties agreed to a visitation schedule for the father.
During the initial custody evaluation, the mother told Stahl she wanted to move with the children to Ohio, where she had grown up, to be closer to her relatives and to take advantage of a lower cost of living. Stahl advised against the move because of the children’s ages (then four and two) and their need to establish a stronger relationship with their father before relocating. Accepting this recommendation, the mother voluntarily postponed her plans.
In December 1996, the trial court awarded primary physical custody to the mother, with continued visitation for the father. Over the next four years, the mother obeyed all court orders for visitation and frequently stipulated to increases in the father’s visitation time with the children. During this time, both parties remarried. The mother married Todd Navarro and they had a daughter, Aisley. The father’s new wife had a daughter from her previous marriage.
In April 1999, the mother and the father stipulated to a second evaluation by Stahl to determine how the children were doing, whether any change in the custody timeshare was appropriate, and whether counseling for the children or the parties was indicated. Stahl’s report, submitted in February 2001, expressed the view that although the children had a good relationship with the mother, their primary caretaker, they did not get along well with the *1103father. In Stahl’s opinion, the children’s difficulties with the father were partly the mother’s fault. Although she was not intentionally subverting the relationship, Stahl thought the mother was unconsciously contributing to the children’s alienation from their father by telling them too much about her disputes with the father and by overindulging them when they expressed negative emotions about the father. Stahl also placed part of the blame on the father, observing that he “is somewhat self-centered and doesn’t seem to deal with the boys’ feelings that well” and that “he is a bit detached from them and has a hard time interacting with them when they are with him, even though he tries reasonably well.”
To remedy this situation, Stahl suggested having the children spend fewer but longer blocks of time with their father during the school year, and equal blocks of time during holidays and during the summer. He also recommended that all disputes be referred to mediation “so that [the parents] can learn problem solving skills and learn to deal with disputes away from their children,” and so that they “learn to disengage from their conflict by trying to parallel parent the boys.” He explained: “With parallel parenting, each parent will strive to do the best job of parenting the boys during the time they are in their respective care, and relinquish the boys to the other parent during the time they are in the other parent’s care.”
In February 2001, the mother requested a modification of the custody order by allowing her to relocate with the boys to Ohio, where her new husband had obtained a better paying job. In March 2001, the trial court ordered a focused evaluation on the mother’s relocation request from Stahl. In a supplemental report, submitted in June 2001, Stahl noted that if the mother moved with the children to Ohio, “[t]heir economic standard of living, and the inherent quality of life, will improve . . . .” He also acknowledged that ordering a custody change to the father would have a significant detrimental effect on the children: “They have been in the primary care of their mother since their parents’ divorce and they will likely have a significant loss [if] she moves without them. They also have a very close relationship with their sister, Aisley, as well as with Todd, and they will feel those losses as well. Third, they certainly have their own desire to move. ... If they don’t move, they’re likely to feel that their wishes aren’t being heard. ... On top of that, they’re likely to blame their dad, potentially increasing their rejection of their dad if forced to stay in California.” Stahl also expressed concern, however, that a move to Ohio could further weaken the children’s relationship with the father. Stahl characterized this relationship as “tenuous at best.”
At an August 2001 hearing, the trial court denied the mother’s request to have her sons move with her, and it ordered a transfer of custody to the father if the mother relocated. The court said it was making this order “to reinforce *1104what is now a tenuous and somewhat detached relationship with the boys and their father.” In explaining its ruling, the court never mentioned the detriment that the boys were likely to suffer in the event of a custody change from the mother to the father.
The Court of Appeal reversed, holding that the trial court had erred by not considering the detriment to the children that would result from a change in custody.
This court granted review.
II
A parent with custody of minor children has a “presumptive right” to change the children’s residence. (In re Marriage of Burgess (1996) 13 Cal.4th 25, 32, 38 [51 Cal.Rptr.2d 444, 913 P.2d 473]; see also Fam. Code, § 7501.) A noncustodial parent opposing such a change of residence bears the initial burden of showing that the move will cause some detriment to the children. (In re Marriage of Burgess, supra, at p. 37.) Once this showing of detriment has been made, the trial court must then weigh the likely effects on the child’s welfare from moving with the custodial parent, against the likely effects from a change in custody. (Id. at pp. 38-39.) Only if the child’s interests are better served by changing custody than by relocating with the custodial parent may a court order custody transferred to the other parent. (Ibid)
Here, the trial court’s explanation for its ruling shows that it properly considered how relocation to Ohio might detrimentally affect the children— including the impact on their tenuous relationship with their father. But the trial court was also required to weigh this detriment against the detriment that would result from removing the boys from the mother’s custody. This the court did not do. In its statement of reasons, the court said: “So I don’t think that I have any real question as to the qualifications or competence of either parent, that is not the issue before me. The issue is the effect on these children of relocating, and the effect of the relationship with their father if they are permitted to relocate.” (Italics added.) But the effect of the relocation on the children’s relationship with the father was not the issue before the court. Rather, it was just one of the potential detriments shown by the evidence that the trial court was required to consider. Equally important was the potential detriment from disrupting the existing custodial arrangement by transferring custody from the mother to the father.
This court has stressed that the “the paramount need for continuity and stability in custody arrangements—and the harm that may result from disruption of established patterns of care and emotional bonds with the primary *1105caretaker—weigh heavily in favor of maintaining ongoing custody arrangements.” (In re Marriage of Burgess, supra, 13 Cal.4th at pp. 32-33.) Here, the trial court’s explanation for its ruling provides no assurance that the trial court gave any weight to the importance of continuity and stability in custody arrangements.
The trial court’s ruling on this custody issue is reviewed for abuse of discretion. (In re Marriage of Burgess, supra, 13 Cal.4th at p. 32.) “The courts have never ascribed to judicial discretion a potential without restraint.” (People v. Russel (1968) 69 Cal.2d 187, 194 [70 Cal.Rptr. 210, 443 P.2d 794].) Rather, “all exercises of legal discretion must be grounded in reasoned judgment and guided by legal principles and policies appropriate to the particular matter at issue.” (Id. at p. 195; accord, People v. Superior Court (Alvarez) (1997) 14 Cal.4th 968, 977 [60 Cal.Rptr.2d 93, 928 P.2d 1171].) Thus, a trial court abuses its discretion whenever it applies the wrong legal standard to the issue at hand. (Linder v. Thrifty Oil Co. (2000) 23 Cal.4th 429, 435-436 [97 Cal.Rptr.2d 179, 2 P.3d 27] [a discretionary order based upon improper criteria or incorrect assumptions must be reversed]; In re Carmaleta B. (1978) 21 Cal.3d 482, 496 [146 Cal.Rptr. 623, 579 P.2d 514] [“discretion can only be truly exercised if there is no misconception by the trial court as to the legal basis for its action”].) It follows that a reviewing court must examine the trial court’s stated reasons for an exercise of discretion to determine whether those reasons reflect a correct understanding of the relevant legal standards and principles. (See, e.g., Linder v. Thrifty Oil Co., supra, 23 Cal.4th 429.)
Concluding that the trial court did not abuse its discretion, the majority says that “nothing in the record before us . . . indicates that the superior court failed to consider the children’s ‘interest in stable custodial and emotional ties’ with their mother.” (Maj. opn., ante, at p. 1092.) But it is equally true that nothing in the record indicates that the court did consider this interest. The majority goes on to state, “In future cases, courts would do well to state on the record that they have considered this interest in stability, but the lack of such a statement does not constitute error and does not indicate that the court failed to properly discharge its duties.” (Ibid., ante, at p. 1092.) I disagree. In the absence of such a statement, or some other evidence in the record showing that the trial court affirmatively considered and weighed the required factors, I cannot conclude that the trial court properly exercised its discretion.
*1106HI
Like the Court of Appeal, I conclude in this case that “[t]he [trial] court’s remarks do not reflect a true ‘best interest’ of the child custody evaluation because they do not give any weight to the presumption favoring continuation of the existing custodial arrangement so that the stability and continuity of the child’s environment is not disrupted.” Therefore, I would affirm the judgment of the Court of Appeal reversing and remanding to the trial court.
Appellant’s petition for a rehearing was denied July 14, 2004. Kennard, J., was of the opinion that the petition should be granted.