Open Source: Unions and Creative Commons?

A question about best practices for official union websites:

Should an official union website be under a creative commons license (share alike, attribution, non-commercial, etc.)?

I think it should. I have a hard time imagining any content a union would not want to make available in this way (assuming a commitment to openness and democracy, a big assumption, I realize).

Most union sites I visit use standard copyright language, and, as I have written about here before, union leaders often try to use copyright/trademark as a justification for retaliation against independent rank-and-file sites, even though the law says otherwise.

Any reasons why a creative commons license would be a problem?