1. A method for processing data in accordance with a privacy policy within a data processing system, the method comprising: receiving, at a proxy, a first message from a first system to a second system; in response to a determination at the proxy that the first message is associated with an operation on personally identifiable information, determining at the proxy whether the operation on the personally identifiable information is compliant with a privacy policy and with user preference information with respect to the privacy policy for a user who is associated with the personally identifiable information, where the personally identifiable information is information that can uniquely identify an individual; in response to a determination that the operation on the personally identifiable information is compliant with a privacy policy and with user preference information with respect to the privacy policy, sending the first message from the proxy to the second system; and in response to a determination that the operation on the personally identifiable information is not compliant with a privacy policy and with user preference information with respect to the privacy policy, sending a second message from the proxy to the first system, wherein the second message indicates an error status.