Wikipedia
Concurrent majority is a constitutional method of enabling minorities to block the actions of majorities by allowing minority groups veto power over laws. In the United States, the most vocal proponents of the theory have tended to be minority groups, such as farmers in an industrial society or slave-owning Southerners protesting national policies that encroached on their hereditary privileges and business interests. The concurrent majority is intended to prevent the tyranny of the majority that can otherwise occur in an unlimited democracy.
Prior to the American Revolution, most governments were controlled by small minorities of ruling elites. In these governments, most of the population was completely disfranchised, even in countries like Switzerland whose governments (local, regional, and federal) were constitutionally democratic by modern standards. The conception of government that materialized during the separation of the United States from the United Kingdom marked movement away from such control towards wider enfranchisement. The problem of tyranny then became a problem of limiting the power of a majority.