The “Mistake Exception” to Judicial Estoppel and the Elevated Hostility Test for Cotenants: A Commentary on Leeks Canyon Ranch, LLC v. Jackson Hole Hereford Ranch, LLC (2025 WY 63)

The “Mistake Exception” to Judicial Estoppel and the Elevated Hostility Test for Cotenants:
A Commentary on Leeks Canyon Ranch, LLC v. Jackson Hole Hereford Ranch, LLC (2025 WY 63)

1. Introduction

In June 2025 the Wyoming Supreme Court handed down Leeks Canyon Ranch, LLC v. Jackson Hole Hereford Ranch, LLC, a decision that addresses two doctrinal flashpoints in property and equity jurisprudence:

  1. Judicial Estoppel – clarifying that the doctrine does not bar a litigant whose earlier inconsistent position stemmed from an honest mistake or forgetfulness, a principle hereafter referred to as the “mistake exception.”
  2. Adverse Possession Between Cotenants – affirming and elaborating Wyoming’s high evidentiary bar for showing “hostile” possession when one cotenant claims to have ousted another.

The dispute concerns a 17.3-acre “Remnant” parcel near Jackson Hole, Wyoming. After complex family trust dealings and an arbitration designed to partition ranchlands, title remained split: Elizabeth Lockhart (through her entity, Leeks Canyon Ranch, LLC) believed she owned 100 % of the Remnant, while her brother Robert Gill quietly retained a 25 % personal interest that he had literally forgotten. When Gill later quit-claimed that interest to Jackson Hole Hereford Ranch, LLC (“JHHR”), litigation ensued.

The Teton County District Court granted summary judgment against Leeks on claims of judicial and equitable estoppel, and—after a bench trial—rejected Leeks’s adverse-possession theory. The Supreme Court affirmed on all issues, thereby crystallising two doctrinal points now binding on Wyoming courts.

2. Summary of the Judgment

  • Judicial Estoppel: The Court adopted, in explicit terms, an exception where the prior inconsistent statement was the product of “inadvertence or mistake.” Because Gill’s earlier arbitration statements were made while he had forgotten his 25 % interest, estoppel could not lie.
  • Equitable Estoppel: The Court reiterated that misrepresentation—intentional or through “culpable negligence”—is required. Simple forgetfulness is “mere negligence,” insufficient to trigger equitable estoppel.
  • Adverse Possession: Although Leeks proved actual, open, notorious, exclusive, and continuous possession for 10 years, it failed the heightened hostility requirement applicable to cotenants. No “clear, positive, and continuous disclaimer” of JHHR’s title was shown.
  • Disposition: District court affirmed in full; JHHR’s 25 % tenancy-in-common interest stands, and partition may proceed.

3. Analysis

3.1 Precedents Cited and Their Influence

  • New Hampshire v. Maine, 532 U.S. 742 (2001) – United States Supreme Court recognised that judicial estoppel may not apply where the earlier position was due to “inadvertence or mistake.” Wyoming adopts this rationale expressly here.
  • Matter of JDV, 2025 WY 46 & Rafter J Ranch HOA v. Stage Stop, Inc., 2024 WY 114 – Wyoming’s recent formulations of the estoppel elements; the Court situates Leeks within that analytical framework.
  • Hatten Realty Co. v. Baylies, 290 P. 561 (Wyo. 1930) & Parkinson v. California Co., 233 F.2d 432 (10th Cir. 1956) – early Wyoming authorities recognising that estoppel does not apply where statements were made “by mistake or without full knowledge.” Leeks re-animates this lineage.
  • Estate of Weeks v. Weeks-Rohner, 2018 WY 112; Ferguson v. Ferguson, 739 P.2d 754 (Wyo. 1987) – cases underscoring the stringent standard for adverse possession among cotenants; cited to show that mere occupancy is insufficient without an unequivocal ouster.

3.2 Court’s Legal Reasoning

  1. Judicial Estoppel
    • Doctrine aims to prevent “playing fast and loose” with the courts.
    • Key element is knowing assertion of inconsistent factual positions.
    • Because Gill’s inconsistent position resulted from forgetfulness, the Court found no culpable intent or manipulation; thus estoppel would not further the doctrine’s purpose.
  2. Equitable Estoppel
    • Requires misrepresentation plus good-faith reliance causing injury.
    • Misrepresentation can be intentional or constitute “culpable negligence,” but must exceed mere inadvertence.
    • Gill’s lapse was, at worst, ordinary negligence; therefore one prong fails, defeating the claim.
  3. Adverse Possession Against a Cotenant
    • Wyoming presumption: cotenants hold mutual rights to possess; one must clearly disclaim the other’s title.
    • District court found Leeks’s actions (tax payments, haying, fencing, exclusive use) suggestive but ambiguous—not a definitive ouster.
    • The contractually described “fences of convenience” and absence of communication to Gill defeated the hostility element.

3.3 Impact of the Decision

Leeks Canyon Ranch will resonate in several arenas:

  • Litigation Strategy: Litigants in Wyoming must now anticipate the “mistake exception.” Counsel will scrutinise whether an opponent’s prior inconsistent statement was truly knowing or instead an honest blunder. Summary-judgment motions invoking judicial estoppel will face this new hurdle.
  • Transaction & Arbitration Drafting: Parties dividing real property via arbitration must memorialise all individual and trust-held interests with precision; reliance on broad oral representations invites later disputes that will not be salvaged by estoppel if mistake can be shown.
  • Adverse Possession Claims Among Cotenants: The case reiterates that paying taxes, maintaining property, and even erecting fences may be inadequate. Prospective adverse possessors must provide unequivocal notice—e.g., recorded quit-claim deeds, explicit written warnings, or lawsuits—to satisfy hostility.
  • Judicial Economy: By limiting estoppel to knowing inconsistencies, the Court balances fairness with judicial efficiency, discouraging gamesmanship yet avoiding punishment for innocent error.

4. Complex Concepts Simplified

Tenancy in Common
Two or more owners each hold an undivided fractional interest in the same property. Each may use the whole; none owns a specific physical slice.
Judicial Estoppel
Bars a party from asserting a position in litigation that contradicts a position successfully asserted in prior litigation when the contradiction is deliberate. New rule: Does not apply if the earlier stance arose from honest mistake.
Equitable Estoppel
Prevents a party from profiting from its own misrepresentation when another relied on it. Requires misrepresentation plus reliance and detriment.
Adverse Possession
A method of gaining title by possessing land in a manner that is actual, open, notorious, exclusive, continuous and hostile for 10 years (in Wyoming). When the parties are cotenants, “hostile” means a clear repudiation of the other’s rights—ordinary use is not enough.
Hostility (in this context)
Not personal animus: it means possession that is inconsistent with and contrary to the true owner’s rights, communicated in a manner that should be understood as a claim of exclusive ownership.

5. Conclusion

Leeks Canyon Ranch, LLC v. Jackson Hole Hereford Ranch, LLC cements two propositions in Wyoming law:

  1. Mistake Exception to Judicial Estoppel: A party who innocently errs about a material fact is not judicially estopped from later correcting that error.
  2. Stringent Standard for Adverse Possession by a Cotenant: Without an unambiguous repudiation of the co-owner’s title, continuous use—even if exclusive—is insufficient to ripen into ownership.

These clarifications promote equitable outcomes—preventing harsh forfeiture for honest mistakes and preserving co-ownership interests absent clear notice of ouster. Practitioners should adjust litigation tactics accordingly: estoppel arguments now demand proof of intentional inconsistency, and adverse-possession claims among cotenants require overt acts that unmistakably proclaim, “I own this and you do not.”

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