From the specification:

The WS-Policy specification defines an abstract policy model and an XML policy expression grammar for making policy assertions. This specification defines a general-purpose mechanism for associating policy expressions with subjects. It provides for two approaches to making the associations: the policy assertions may be defined as part of the definition of the subject or the policy assertions may be defined independently and associated through an external binding to the subject.

To enable WS-Policy to be used with existing Web service technologies, this specification describes the use of these general-purpose mechanisms with WSDL and UDDI. Specifically, this specification defines the following:

• How to reference policies from WSDL definitions
  
• How to associate policies with specific instances of WSDL services
  
• How to associate policies with UDDI entities