Here is a link to SEIU protesters getting arrested in Wisconsin.
The key thing moving public opinion in the public unions' favor is the idea of rights. Taking away someones rights always seems to strike the public as unreasonable. Simply by calling an arrangement a right inclines public opinion to favor continuing the arrangement regardless. Framing the argument as a fight to prevent "taking away collective bargaining rights," stacks the deck in favor of the public union side of the debate.
The problem here is not only that anything can be called a right, but that any right for one group by definition takes away another right. In the case of 'collective bargaining rights' the reciprocal is 'individual bargaining rights.' The supporters of Governor Walker should answer the charge that they are "taking away collective bargaining rights" by saying they are "restoring individual bargaining rights."