Tyranny of the majority
From Metagovernment - Government of, by, and for all the people
The phrase "tyranny of the majority," used in discussing systems of democracy and majority rule, is a criticism of the scenario in which decisions made by a majority under that system would place that majority's interests so far above a minority's interest as to be comparable to "tyrannical" despots. See the Wikipedia article on Tyranny of the majority.
Tyranny of the majority is a frequent criticism of direct democracy and to some extent most current forms of democracy.