Oral, Preliminary Assurances—Especially Where a Writing Is Expected—Do Not Satisfy Wyoming Promissory Estoppel

1. Introduction

Four B Properties, LLC; Ranch 10, LLC; Gary A. Binning v. The Nature Conservancy is a diversity appeal in which the Tenth Circuit affirmed summary judgment against a landowner seeking to enforce an alleged oral “workaround” to a conservation easement through promissory estoppel. The dispute arose after the Wyoming Supreme Court had already authoritatively interpreted the easement to permit only one single-family residential structure per parcel, excluding guest houses and similar residential outbuildings.

The plaintiffs (collectively “Binning”) owned land burdened by a conservation easement held by defendant The Nature Conservancy (“TNC”). After losing state-court litigation over whether the easement allowed a guest house, Binning claimed that TNC’s new state director orally indicated over lunch that he could proceed with a guest-accommodating structure so long as he did not call it a “guesthouse,” avoided a kitchen, and complied with local land development regulations. When TNC later refused to approve Binning’s “kitchenless wellness center” plans (which TNC viewed as residential in substance), Binning sued in federal court seeking to bind TNC to the alleged oral assurances via promissory estoppel.

The key issues on appeal were whether Binning could show (1) a clear and definite promise that TNC should reasonably expect to induce action, (2) reasonable detrimental reliance, and (3) whether injustice can be avoided only by enforcement, as required under Wyoming law.

2. Summary of the Opinion

The Tenth Circuit affirmed. Applying de novo review of summary judgment, the court held that Binning failed on each of promissory estoppel’s three elements:

  • No clear and definite promise / no reasonable expectation of inducement: the alleged lunch statements were at most “conditional and inchoate,” made in a preliminary negotiation context, and surrounded by circumstances showing both sides contemplated written confirmation and legal review.
  • No reasonable reliance: given the parties’ extensive litigation history, Binning’s sophistication, his distrust of TNC, and the later written communication from TNC that did not memorialize the alleged promise, any reliance on an oral “go ahead” was unreasonable.
  • No equitable necessity: because Binning could not establish the first two elements, there was no basis to invoke equity to enforce the alleged promise.

3. Analysis

3.1. Precedents Cited

A. Governing promissory estoppel framework (Wyoming law)

  • Singer v. Lajaunie (quoting City of Powell v. Busboom): supplied the controlling three-element test for Wyoming promissory estoppel and the allocation of roles—first two elements as fact questions, the third as a legal/equitable determination for the court.
  • Inter-Mountain Threading, Inc. v. Baker Hughes Tubular Servs., Inc.: provided two key doctrinal points that drove the outcome: (i) the first element’s “dual emphasis on clarity and inducement,” and (ii) the insufficiency of “mere expressions of hope and opinion in an obviously preliminary negotiation context.” The court treated the lunch conversation as precisely that kind of preliminary, non-committal context.
  • Davis v. Davis (and Roth v. First Sec. Bank of Rock Springs): tied “reasonable reliance” to the definiteness of the promise and instructed that reliance must be evaluated under the totality of circumstances, including the “knowledge and sophistication of the relying party.” This supported the court’s focus on Binning’s sophistication and the dispute’s litigation history.
  • Brown v. Royal Maccabees Life Ins. Co.: supplied the phrase “conditional and inchoate representations” to characterize statements too indefinite to constitute a promissory estoppel promise. The court used this characterization to reject the “Baseline Promise” theory.
  • Rialto Theatre, Inc. v. Commonwealth Theatres, Inc.: reinforced that an “agreement to agree in the future” is not a clear and definite promise. The court viewed the lunch discussion, followed by an expected written follow-up and legal review, as pointing toward future agreement rather than present commitment.
  • Doud v. First Interstate Bank of Gillette: supported considering parties’ prior course of dealing and “typical business practice” in assessing whether a promisor should expect reliance. Here, a history of contentious dealings and formal litigation made reliance on an unwritten lunch statement implausible.

B. The prior authoritative easement interpretation shaping the dispute

  • Four B Props., LLC v. Nature Conservancy, 458 P.3d 832 (Wyo. 2020): while not a promissory estoppel precedent, it was the legal backdrop that made the alleged promise inherently fraught. The Wyoming Supreme Court had held “as a matter of law” that the easement permits only “a single building in which one family can live and dwell,” and that “associated improvements” do not include residential structures like guest houses. The Tenth Circuit repeatedly treated that binding interpretation as contextual evidence that any informal assurance to “work around” the decision would not reasonably induce reliance absent a clear, formal commitment.

C. Standards of review, procedure, and Erie

  • Am. Sw. Mortg. Corp. v. Cont'l Cas. Co., Sanderson v. Wyo. Highway Patrol, and Jones v. Norton: supplied federal summary judgment principles—de novo review, viewing evidence favorably to the non-movant, and “genuine dispute” meaning a rational jury could find for the non-movant.
  • Banner Bank v. Smith and Erie R.R. Co. v. Tompkins: grounded the court’s methodology—federal procedure, Wyoming substantive law.

D. The “strict proof” discussion (burden of persuasion)

  • Orthopaedics of Jackson Hole, P.C. v. Ford and Grocery Outlet Inc. v. Albertson's Inc.: used to illustrate that Wyoming uses “strict proof” language in promissory estoppel cases but has not clearly pegged it to a familiar evidentiary standard. The Tenth Circuit assumed (without deciding) that the preponderance standard applied, making its affirmance more robust: even under the more plaintiff-friendly assumption, Binning still could not prevail.

E. Reliance versus subsequent writings

  • Woodward v. Chesapeake Operating, LLC: supported the proposition that reliance is unreasonable where oral statements conflict with later written representations. The court used this to underscore that TNC’s post-lunch letter—framed as “additional guidance” and conditioned on review—undercut any claimed reliance on an oral green light.

F. Equity and limits on summary judgment on the third element

  • Verschoor v. Mountain W. Farm Bureau Mut. Ins. Co.: recognized the breadth (but not absoluteness) of equitable authority and, critically, that a court should not grant summary judgment solely on the third element where the first two elements raise material fact disputes. The Tenth Circuit distinguished that scenario: because Binning failed on elements one and two, equity could not salvage the claim.

3.2. Legal Reasoning

A. Element One: clear and definite promise + reasonable expectation of inducement

The court accepted, for summary judgment purposes, that the lunch statements were made (TNC did not seek to impeach the testimony and the court drew inferences in Binning’s favor). The problem was legal sufficiency: the statements were not “clear and unambiguous in their terms,” but rather conditional and situated in a negotiation framework where both parties anticipated subsequent written clarification and legal vetting.

Several contextual facts were decisive:

  • Binning asked for “something in writing” due to perceived past untrustworthiness by TNC.
  • Mortimer indicated she would run anything through counsel and qualified staff.
  • The parties were negotiating in the shadow of years of litigation and an adverse, controlling state supreme court decision.
  • TNC’s subsequent letter described the conversation as a request for “additional guidance,” and proposed only conditional non-objection “subject to a review of actual plans and confirmation with Teton County.”

On these facts, the court held no rational jury could find a clear and definite promise that TNC should reasonably expect to induce action.

B. Element Two: reasonable detrimental reliance

Even assuming substantial expenditures, the reliance had to be reasonable. The court stressed that reliance is “closely tied” to promise definiteness and assessed reasonableness under all circumstances, including Binning’s sophistication and the parties’ litigation history.

The court found reliance unreasonable because:

  • Binning was sophisticated (“buy[s] companies for a living”).
  • He had already litigated and lost on the same easement issue up to the Wyoming Supreme Court.
  • He distrusted TNC and specifically wanted a writing.
  • The written follow-up did not memorialize the alleged permission and instead conditioned any position on review and compliance with the “one structure” concept.
  • The alleged oral assurance was in tension with the Wyoming Supreme Court’s authoritative easement interpretation.

C. Element Three: injustice avoidable only by enforcing the promise

The third element is equitable and reserved to the court, but it does not operate as an escape hatch when the first two elements fail. Because Binning could not establish a triable issue on promise or reliance, the court held there was no equitable basis to compel enforcement against TNC.

3.3. Impact

  • Constraining “workarounds” to conservation easements: The decision signals that promissory estoppel will not readily be used to circumvent a conservation easement’s judicially-declared meaning—especially where the alleged promise is informal and ambiguous.
  • Elevating the importance of writings in high-stakes land-use disputes: Where parties explicitly contemplate written confirmation (and legal review), reliance on oral assurances is unlikely to be deemed reasonable. This encourages conservation holders and landowners to formalize any interpretive accommodations.
  • Negotiation behavior after litigation matters: Post-judgment discussions framed as “guidance” and followed by conditional letters will be treated as preliminary negotiations, not enforceable promises—reducing the risk that routine stakeholder conversations generate estoppel liability.
  • Litigation strategy: Plaintiffs asserting promissory estoppel in Wyoming should expect courts to scrutinize (i) definiteness, (ii) whether the promisor should expect inducement, and (iii) whether subsequent writings contradict the alleged promise—often making summary judgment a realistic defense tool.

4. Complex Concepts Simplified

  • Conservation easement “running with the land”: A recorded restriction that binds future owners, not just the original grantor. Buying the property means buying the limits.
  • Promissory estoppel: An equitable doctrine that can enforce certain promises even without a contract, but only when there is a clear promise, reasonable detrimental reliance, and enforcement is necessary to avoid injustice.
  • “Clear and definite promise”: Not a general assurance or hopeful statement. It must be specific enough that a reasonable person can tell what is being promised and on what terms.
  • Reasonable reliance: The law asks whether it was sensible to act on the promise in context—considering sophistication, the need for a writing, contrary documents, and known legal constraints.
  • Summary judgment: A case can be decided without trial if, even crediting the non-movant’s evidence, no reasonable jury could rule for them on a required element.
  • Erie doctrine: In diversity cases, federal courts apply state substantive law (here, Wyoming promissory estoppel) but federal procedural rules (summary judgment standards).
  • “Strict proof”: Wyoming describes the plaintiff’s burden in promissory estoppel as “strict,” but has not precisely defined whether it means more than a preponderance; here the Tenth Circuit assumed the lower (preponderance) burden and still found the claim deficient.

5. Conclusion

The Tenth Circuit’s decision reinforces a practical rule for Wyoming promissory estoppel claims: informal, conditional assurances made in a preliminary negotiation setting—particularly where the parties expect a writing and the subject is constrained by an existing judicial interpretation—will not be treated as clear, inducement-worthy promises, and reliance on them will not be deemed reasonable.

In the broader land-use and conservation-easement context, the opinion underscores that post-litigation “let’s move forward” conversations do not, without clear and definite commitment, rewrite recorded restrictions or overcome authoritative state-court interpretations through equity alone.