A Wyoming landowner claimed a conservation group promised he could build a guest house without a kitchen; federal appeals court rejected his claim

A Wyoming landowner’s attempt to build a second residential structure on conservation land led to years of litigation with The Nature Conservancy (TNC). Gary Binning wanted to build a guest house on property subject to a conservation easement, which restricted construction to one single-family residential structure per parcel.After losing an earlier case before the Wyoming Supreme Court, Binning said TNC’s state director had orally agreed he could build a structure for overnight guests if it was not called a guest house and had no kitchen.According to the US Court of Appeals for the Tenth Circuit dated 15 April 2026, the court rejected Binning’s appeal, finding that the alleged promise was not sufficiently clear and that relying on it was unreasonable. The ruling upheld the district court’s judgment in favour of TNC.Wyoming landowner faced restrictions on guest house construction on 500-acre ranchThe dispute began with a 500-acre Wyoming ranch between the Snake River and Grand Teton National Park. A conservation easement was established on the land to protect its natural, scenic, or open-space values. The easement allowed an owner to construct one additional single-family residential structure on each subdivided parcel, alongside associated improvements.In an earlier case, the Wyoming Supreme Court interpreted that wording as permitting only one building in which one family could live. It ruled that associated improvements did not include another residential structure, such as a guest house or caretaker’s quarters.Guest house dispute centred on an alleged promise by TNC directorAfter the Wyoming Supreme Court ruling, Binning continued seeking a way to accommodate overnight visitors. He and his wife, Marianna, later met TNC’s Wyoming state director, Hayley Mortimer, for lunch in Jackson. Binning testified that Mortimer wanted to resolve the dispute and said he could build a structure if he did not call it a guest house, left out a kitchen, and followed Teton County’s Land Development Regulations.Marianna also recalled similar comments. Mortimer did not remember making the alleged promise. She said she had told Binning that she needed to consult the organisation’s lawyers and qualified staff before following up. Her later letter described the meeting as a request for additional guidance about the property’s development at that stage.A kitchenless design failed to resolve the Wyoming building disputeIn her letter after the lunch, Mortimer said TNC would not object to a design if Teton County approved it as one single-family residential structure rather than multiple accessory residential units. Binning sought changes to the letter but did not refer to the alleged lunchtime promise in his response. He later asked his architects to design a “kitchenless wellness centre” where guests could stay overnight.Teton County approved permits for three buildings in July 2022, including a gym and yoga studio with about 2,500 square feet of habitable space. TNC rejected the wellness centre plans, pointing to four rooms with adjoining bathrooms, laundry facilities and food-preparation features.Appeals court rejected landowner’s claim over alleged verbal promiseBinning sued, arguing that promissory estoppel should prevent TNC from blocking the building. Under Wyoming law, the claim required a clear and definite promise, reasonable reliance that caused detriment, and a finding that enforcement was necessary to avoid injustice. The Tenth Circuit said the lunch comments were conditional and did not represent a definite commitment.It also found reliance unreasonable because Binning had years of litigation behind him, wanted written confirmation, and knew the alleged oral agreement conflicted with the Wyoming Supreme Court ruling. TNC’s follow-up letter did not confirm the promise, and Binning’s correspondence did not mention it.You use AI every day. Now get your AI Quotient. Take the AIQ test.