On the basis of your knowledge of contracts, describe the following case. Be sure to assist your view with the facts and the law.

Maurice is an accountant who workings for the firm of Addum, Upp, & Paymee. Maurice was approached by Shirley Eugest who represents one of Addum's competitors, BeanCounters, Inc. Maurice was offered a substantial increase to leave his company and work for BeanCounters. When Maurice's boss heard this he called him in as well as said If you stay with us, I assure that next year you will receive a promotion with a 50% raise, and a 5-year contract. Maurice turned down the proposal from BeanCounters and stayed with Addum. Nine months later Maurice was terminated due to corporate downsizing. Can Maurice lawfully enforce his boss's promise? What theory or else theories would Maurice use? Discuss fully.