Labor Union

aka Trade Union

created to protect the Common Man for unsafe working conditions and other abuses of "Power".

often end up run by Organized Crime, because that's where the money is

http://www.wikipedia.org/wiki/Labor_union

key tool: Labor Strike

Often appear more interested in maximizing income from dues over anything else. Secondarily "protecting" employees by evaluation from their actual managers, so that assignments and pay get driven more by seniority than ability, quality, etc.

special case: Government Union