Apache Commons Neethi:

This is an implementation of WS-Policy Specification (March, 2006) which 
can be located at:http://specs.xmlsoap.org/ws/2004/09/policy/ws-policy.pdf

It provides a convenient model and an API to process policy information at 
runtime and an extension model for serailization and de-serialization of 
domain specific Assertions. 

This framework is heavily used in Apache Axis2, Apache Sandesha2, 
Apache WSS4J (as an experimental feature) and now gaining its maturity.

Please visit : http://ws.apache.org/commons/neethi/ for further infomation.