Unanimous consensus criterion

Definition

A voting system that guarantees the election of an alternative that is consented to by all voters in the voting population satisfies the unanimous consensus criterion.

An alternative that is consented by all voters is called a unanimous consensus winner. It is possible that no such winner exists in a given election. Also, in a given election with two or more alternatives, there can exist more than one unanimous consensus winner. Voting systems that guarantee the election of a unanimous consensus winner must have a tie-breaking mechanism among multiple winners in order to be decisive.

Approval voting and Llull Voting satisfy the unanimous consensus criterion. Condorcet methods, Plurality voting, IRV, and the Borda count do not satisfy this criterion.