The trust disputes study offers a rare window into how family trusts unravel, finding that certain common estate-planning choices, especially appointing one child to control a trust that benefits multiple relatives, frequently lead to conflict.
Researchers analyzed 640 contested trust matters scheduled before San Francisco Superior Court between 2014 and 2020, according to the paper published this month in the Washington University Law Review. The authors, law professors Christopher Ryan of Indiana University Maurer School of Law, Reid Weisbord of Rutgers Law School, and David Horton of the University of California, Davis, School of Law, said naming a single descendant as trustee over siblings or other heirs is often a flashpoint.
Ryan described that arrangement as a recipe for tension when ordinary sibling rivalry intersects with real authority over distributions. He noted that granting one child discretion over payouts can intensify existing perceptions of parental favoritism.
Trust disputes study highlights trustee-misconduct claims
Nearly one quarter of the reviewed petitions involved a descendant beneficiary suing another descendant beneficiary who also served as trustee, Horton said. Many litigants were siblings, including step- or half-siblings, though some were grandchildren. Nearly all filings concerned revocable trusts, a prevalent vehicle that allows a successor trustee to administer a settlor’s property after death.
While trusts are often used to bypass probate, the cases show families can become entangled in lengthy and expensive battles. The average matter, including those that settled, lasted 481 days.
In 74% of petitions, trustees faced allegations of misconduct, frequently for breach of duty of care or loyalty. In nearly one third of cases, beneficiaries sought a detailed accounting, which Horton said often reflected suspicions that trustees were mismanaging or diverting funds.
Emotions, litigation outcomes, and a cautionary case
Horton observed that many fights appeared to be driven more by emotion than by dollars. He pointed to the prolonged dispute among the Mar siblings, which consumed the trust’s cash and stretched for more than five years. Raymond Mar, who died in 2016, granted his son a lifetime right to live rent-free in his home. A disagreement over whether the son could accept a tenant sent the family to court. In 2024, a judge criticized both sides for excessive litigation, ordered the trust dissolved, and directed the house be sold. Despite that ruling, Mar’s daughters filed in October 2025 to deduct attorney fees from their brother’s share.
The data suggest litigants’ feelings can cloud judgment. When parties refused to settle and proceeded to a formal trial, petitioners who challenged the trust generally fared worse. The study found their likelihood of winning or settling fell by 48 percentage points compared with cases decided on filings and oral arguments without a full trial.
The authors estimated that as many as three quarters of petitions ultimately settled. The precise figure is uncertain because roughly one third of cases dropped from the docket without a merits ruling, which the researchers believe frequently indicates settlement.
Preventing conflict and the limits of no-contest clauses
To reduce the risk of family strife, the authors recommended that parents consider frank discussions about their plans and weigh appointing an independent or professional fiduciary. “Death brings out strong emotions,” Horton said, adding that explaining choices while alive can surface and address brewing disagreements.
Ryan cautioned that no-contest clauses, which threaten to disinherit beneficiaries who sue, are not a cure-all. Their enforceability varies by state, he said, so parents should not assume they will deter litigation.
Mediation stood out as effective. The study found that 85% of matters that went to mediation settled, compared with 47% of cases without it. “I would plan for conflict rather than assuming drafting can eliminate it,” Ryan said. For some families, choosing to keep significant decisions and life milestones offline may also help limit misunderstandings and outside pressures.