Business Law 13th Edition by Frank Cross, Kenneth Clarkson, Roger LeRoy Miller

Exercise 13

John operates a motorcycle repair shop from his home but finds that his business is limited by the small size of his garage. Driving by a neighbor's property, he notices a for-sale sign on a large, metal-sided garage. John contacts the neighbor and offers to buy the building, hoping that it can be dismantled and moved to his own property. The neighbor accepts John's payment and makes a generous offer in return: if John will help him dismantle the garage, which will take a substantial amount of time, he will help John reassemble it after it has been transported to John's property. They agree to have the entire job completed within two weeks. John spends every day for a week working with his neighbor to disassemble the building. In his rush to acquire a larger workspace, he turns down several lucrative repair jobs. Once the disassembled building has been moved to John's property, however, the neighbor refuses to help John reassemble it as he originally promised. Using the information presented in the chapter, answer the following questions.
Suppose that the neighbor starts to help John but then realizes that, because of the layout of John's property, putting the building back together will take much more work than dismantling it took. Under which principle discussed in the chapter might the neighbor be allowed to ask for additional compensation?