Final answer:
Sullivan relied on a verbal promise from Jackson to sell property, which is typically not enforceable under the Statute of Frauds. However, the doctrine of promissory estoppel might apply, as Sullivan made improvements based on that promise, potentially preventing Jackson from reneging on the agreement.
Step-by-step explanation:
In the scenario described, Sullivan made significant improvements to the property based on a verbal agreement with Jackson to purchase it. However, verbal agreements for the sale of real property are often not enforceable due to the Statute of Frauds, which requires written contracts for such transactions. This legal principle is aimed at preventing fraud and misunderstandings in contracts concerning real estate. Despite the Statute of Frauds, Sullivan may invoke the legal doctrine of promissory estoppel. This means that because Sullivan reasonably relied on Jackson's promise and made improvements to the property, Jackson might be estopped from denying the sale. The court could potentially enforce the agreement to prevent Jackson from benefiting unfairly from Sullivan's reliance on his promise.