In Europe there's an interesting development in the non-discrimination legislation. While at the moment it only applies in the context of employment, it's in the works being extended to other areas. It's the concept of 'instruction to discriminate'. If an institution of any kind instructs its members / affiliates / students to discriminate based on, among other things, religion and belief, that in itself will be considered a crime. It is an easy thing to demonstrate that shunning an ex-JW is a differentiated treatment than that given to a 'wordly' person who was never a JW, and, therefore, discrimination. The crime is considered to be perpetrated indirectly, that is, by the institution that is teaching or instructing to discriminate.
Edenone This is really interesting. I guess it could be classed as discrimination due to religon/belief system. As Mickeymouse mentioned, almost impossible to legislate on an individual basis but do-able when it comes to organizations that instruct its members to shun. Certainly it could be used as a reason to take away an organizations charitable statu - as is being talked about with regard to orgs that lack good child protection practices.