Business cases should be required for all work outside of routine maintenance and minor enhancements. Business cases are the instruments through which project priorities are set and are created by a joint business unit/technology team. Remember, it's a business case, not a technology case. Business cases are required to address questions of enterprise business goals and technology goals. The business case process forces individuals and organizational units to engage in a continuing dialogue.
Alignment with business objectives is a natural consequence of jointly developed business cases for projects that fall within the strategic plan of the business. Approval of the business case moves the business agenda forward and creates partnership and understanding during the process. A significant objective of this process is the respect of the business for IT's understanding of the business and its strategic needs.