Most societies are structured in a hierarchal way- people with higher status possess more power and authority. The authority they yield is legitimate-agreed on by society. We accept that authority figures having more power allows society to run smoothly from childhood. Therefore some people are granted to have the power to punish others (courts and police) , we are willing to give up some of our independence and hand over control of our behaviour to people who we believe will exercise their power appropriately.
History often shows reruns of how charismatic and powerful leaders can abuse their legitimate powers for destructive and dangerous purposes-ordering people to act in cruel ways. Destructive authority was obvious in Milgram's experiment: the expenmenter used prods to order participants to behave in ways that went against their consciences.
