When a Probate Court Locks Out a Surviving Parent: Nichols v. Slavicek and Why Rule 24 Still Matters in Conservatorship Disputes

By Kent Berk on May 5th, 2026 in BLOG, conservatorship, Estate Litigation, Fiduciary Litigation, guardianship, PROBATE LITIGATION

Intervention issues don’t arise often in Arizona probate Court. Nichols v. Slavicek, No. 1 CA-CV 25-0272 PB (Ariz. App. May 4, 2026) (mem. decision), is a sharp reminder that the rules apply and probate courts cannot quietly sideline a surviving parent from cases involving her own minor children. Even in an unusual procedural posture, and even when a guardian ad litem and a law firm say they have things under control. Division One vacated the superior court’s denial of a mother’s motion to intervene, holding that her constitutional and statutory parental rights, combined with the liberal construction of Arizona Rule of Civil Procedure 24(a), made intervention a matter of right.

The Backdrop

The case grows out of a tangled set of family, civil, and probate proceedings:

2017: Mother and Father divorced, stipulating to joint legal decision-making for their three minor children.
2020: Mother and the children were in a car accident; the children were injured.
2022: Father, on behalf of the children, sued Mother for negligence, including allegations of intoxicated driving and retained the Slavicek Law Firm to prosecute the tort claim.
During the civil case, Mother objected to a medical examination of one child. Father then petitioned the probate court to be appointed conservator so he could manage the litigation. The probate court denied that petition “at this time,” noting Father had not used civil discovery tools first.
Less than a year later: Father died unexpectedly.

After Father’s death, two competing tracks lit up in probate:

Mother filed three petitions (one per child) asking that her brother be appointed conservator so he could “compromise a settlement” of the children’s tort claims.
The Firm petitioned in Father’s dormant probate case to have a guardian ad litem appointed, asserting that it “represents the minor children” because it had been “hired by the minors’ father.”

The probate court consolidated all four cases, appointed a guardian ad litem (GAL) on its own motion under A.R.S. § 14-1408, and directed the GAL to investigate whether the Firm had authority to keep acting as the children’s counsel. The GAL concluded that the Firm “may be an interested party” under A.R.S. § 14-1201(34), recommended the Firm continue in its role, and offered to sign a “new engagement agreement” with the Firm if needed. Over Mother’s objection, the court expanded the GAL’s authority to manage the civil lawsuit and to retain a personal injury firm and the GAL then retained the Firm.

Mother voluntarily dismissed her conservatorship petitions and moved to intervene under Civil Rule 24(a) in the remaining consolidated probate matter, citing constitutional and statutory authority. The probate court denied her motion and entered Rule 54(b) judgment. Mother appealed.

What the Court of Appeals Held

The Court of Appeals vacated and remanded in a memorandum decision. Three pieces of the analysis matter for probate, trust, and guardianship litigators.

1. Briefing imperfections didn’t kill the appeal

The Firm asked the court to find waiver, arguing Mother’s opening brief failed to expressly cite Rule 24 or specify which subpart applied. The panel acknowledged the brief could have been more careful but reached the merits anyway, citing the Aubuchon “bona fide and reasonably intelligent effort” standard, the discretionary nature of waiver. Pointedly, the also relied on the fact that “fundamental rights are at stake” and the court “must always account for the best interests of children” The Firm’s untimeliness argument fared no better: it was raised for the first time on appeal and unsupported by any showing of prejudice.

2. A surviving parent has an unconditional right to intervene in her children’s probate proceedings

Rule 24(a)(1) requires intervention where a movant has an unconditional statutory right; Rule 24(a)(2) requires it when the movant claims an interest that disposition without her would impair, unless adequately represented. The panel found Mother satisfied the first prong on multiple, overlapping grounds:

The Fourteenth Amendment protects a parent’s fundamental liberty interest in the care, custody, and management of her children.
The Arizona Parents’ Bill of Rights, A.R.S. § 1-601, requires any infringement on those rights to satisfy strict scrutiny.
The third “catch-all” category of “interested person” in A.R.S. § 14-1201(34) is intentionally flexible and “must be determined according to the particular purposes of, and matter involved in, any proceeding,” broad enough to capture a surviving parent.
Upon the death of one custodial parent, sole legal decision-making automatically passes to the surviving parent. After Father’s death, Mother held that authority for her children.

Layered together, these authorities meant Rule 24(a) — which is “remedial and should be liberally construed” entitled Mother to intervene as of right.

3. “We’ll send her notice” is not due process

The probate court told Mother it “intends for [her] to receive notice of pleadings.” The panel was unimpressed: the court “never guaranteed she would receive them or provided her an avenue to be heard.” Due process requires “the opportunity to be heard at a meaningful time and in a meaningful manner.” Informal notice is not a substitute for party status.

The panel also dispatched the Firm’s argument that “a parent has no right under the due process clause to inflict conflicts of interest upon their children,” noting it was unsupported by Arizona authority and that the Firm itself acknowledged Mother is “an interested person” who is “perfectly free to file papers seeking dismissal of the GAL (or other relief).” That admission, the court observed, supports, rather than defeats, intervention as of right.

Practical Takeaways for Arizona Probate, Trust, and Guardianship Litigators

Parental status is more than procedural status. A surviving parent with sole legal decision-making authority is not just a stakeholder to be “kept informed.” She is constitutionally and statutorily entitled to be a party in probate proceedings centered on her minor children.
Rule 24(a) is liberally construed in probate. When fundamental rights and children’s best interests intersect, Arizona courts read the rule generously.
Section 14-1201(34) cuts in multiple directions. The “interested person” definition is broad enough to embrace not only law firms claiming pre-death engagements, but also surviving parents asserting parental authority. Litigators on either side should expect courts to apply the definition contextually.
Don’t outsource a parent’s voice to a GAL. A GAL’s conclusion that one party “should continue” in a representational role does not displace the parent’s right to be heard, particularly where the GAL’s recommendation drives directly back to the firm originally retained by the deceased parent.
“Notice” without a right to be heard is not due process. If a probate court tells a parent it “intends” to keep her in the loop while denying intervention, that’s a red flag — and now an appellate roadmap.
Intervening doesn’t equal winning. The court was clear: allowing Mother to intervene “does not mean the superior court must grant her requested relief.” The merits, including whether the GAL should be removed and whether the Firm was properly involved, remain to be litigated on remand.
Memorandum decision, but useful reasoning. Nichols is non-precedential, but the synthesis of the analysis in the context of Rule 24 is a useful template for anyone briefing a surviving-parent intervention question.

Why This Matters at Berk Law Group

We focus exclusively on Arizona probate, trust, estate, guardianship, conservatorship, and fiduciary litigation. Cases like Nichols v. Slavicek sit squarely at the intersection of several of our core practice areas.

If you are a surviving parent who feels shut out of a conservatorship or guardianship proceeding involving your children, a fiduciary trying to navigate competing claims of authority, or counsel facing an intervention fight under Rule 24 in an Arizona probate case, the procedural posture matters as much as the substantive merits. Getting your client to the table with full party status is often the whole ballgame.

Contact Berk Law Group for a confidential consultation. We have spent more than 30 years helping Arizonans protect their families, their fiduciary roles, and their rights in court.