Every Celt was considered free upon birth as their right.  The Druidic leadership was a unifying force that bred loyalty within each tribe.  Elections took place in a fairly democratic system.  The people elected their chiefs and the chiefs then nominated a king.  Sounds pretty good for the people, but not always for the king; he could be deposed any time the people got together and deemed him incompetent or simply felt like he was doing a lousy job.