referendum, referral of proposed laws or constitutional amendments to the electorate for final approval. This direct form of legislation, along with the initiative, was known in Greece and other early democracies. Today, these legislative devices are widely used in certain countries, most notably Switzerland. Their use in the United States reached a peak in the early part of the 20th cent. In the United States there are two main types of referendum—mandatory and optional. The mandatory referendum may be required by state constitutions and city charters for a variety of matters. It usually applies to constitutional amendments and bond issues, which by law have to be placed before the voters for approval. The optional referendum is applied to ordinary legislation. By the usual procedure implementation of a law is postponed for a certain length of time after it has been passed by the legislature; during this time, if a petition is presented containing the requisite number of names, the proposed legislation must be put to a vote at the next election.

Electoral devices by which voters express their wishes regarding government policy or proposed legislation. Obligatory referenda are those required by law. Optional referenda are put on the ballot when a sufficient number of voters sign a petition demanding that a law passed by the legislature be ratified by the people. Obligatory and optional referenda should be distinguished from the voluntary referenda that legislatures submit to voters to decide an issue or to test public opinion. Initiatives are used to invoke a popular vote on a proposed law or constitutional amendment. Direct initiatives are submitted directly to the public after approval by a required number of voters; indirect initiatives are submitted to the legislature. Switzerland has held about half the world's national referenda. Referenda also are common at the local and state level in the U.S. In the late 20th century, referenda were employed more frequently, particularly in Europe, to decide public policy on voting systems, treaties and peace agreements (e.g., the Maastricht Treaty), and social issues. Seealso plebiscite.

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