Business rules are statements about the enterprise's way of doing business. They become requirements that govern the operational system of the enterprise and determine constraints for any system developed or procured for an enterprise. This paper addresses an architecture for the specification, enforcement and distribution of business rules, as a way of achieving the interoperability of distributed information systems that support an enterprise. We explore the XML encoding of business rules, which allows their multiple representations, necessary for dealing with the heterogeneity of software and platforms inherent in large companies, or in e-commerce applications. Our ideas are illustrated with examples implemented in Oracle's framework for developing e-business solutions.