Referendum
Participation quorum

Referendums may require a turnout threshold (also called a participation quorum) in order for the referendum to be considered legally valid. In a participation quorum a majority of those voting must approve of the referendum, and a certain percentage of population must have voted in order for the results to be approved.

The usage of participation quorums in referendums is controversial, as higher requirements have been shown to reduced turnout and voter participation. With high participation quorums, the opposition of a referendum has an interest in abstaining from the vote instead of participating, in order to invalidate the referendum results through low turnout. This is a form of the no-show paradox. All others who are not voting for other reasons, including those with no opinion, are effectively also voting against the referendum.

In the 2005 Italian fertility laws referendum, opposition to the proposed loosening of laws on research on embryos and on allowing in-vitro fertilization, campaigned for people to abstain from voting to drive down turnout. Although a majority of people voted yes for the changes in the law, the results were invalid because participation was low.
oulipo:avoid_letter[t]