http://en.wikipedia.org/wiki/Union_Democracy

http://en.wikipedia.org/wiki/Iron_law_of_oligarchy#Examples_and_exceptions

excerpt :

"The book addresses the factors that influence the power structure and decision making processes in organizations, with a specific focus on the political systems of democracy and oligarchy. The problem seen as central by the authors was the difficulty of maintaining democracy in organizations. The issue was first raised by Robert Michels in his Political Parties and termed the Iron law of oligarchy: all forms oforganization, regardless of how democratic or autocratic they may be at the start, will eventually and inevitably develop into oligarchies"...