The role of fault is undeniable in different parts of the law of contracts in U.S.A. One of these parts is the doctrine of impossibility and unexpected circumstances. Fault regime is more equitable than other regimes such as strict liability, because it doesn`t impose the whole liability on the promisor but impose it on the person who is at fault. According to the doctrine of impossibility, if the promisor is able to predict the accident but avoid doing this, he will be obliged to compensate the promisee for the total loss. And if the promiseeis in a better position to predict the accidents but avoids doing this, he is at fault and will be deprived of receiving damages to the extent of his fault. If no one is at fault, the promisor should pay the reliance damages to the promisee in order to return him to the situation that he had before the conclusion of the contract.