What are the unions supposed to do?

"When Dave Prentis says he intends to bring "huge swaths of the public sector to a halt", he isn't making idle threats. #uNDC11 He can, and he will’ writes Dan Hodges on the New Statesman website. Hodges responds to recent media attacks on public sector unions: http://www.newstatesman.com/blogs/dan-hodges/2011/06/needs-union-members-rights