One person, one vote

One man, one vote (or one person, one vote) is a principle of political democracy that underpins universal suffrage and political equality. During the 20th-century period of decolonisation and the struggles for national sovereignty, from the late 1940s onwards this phrase became widely used in developing countries where majority populations sought to gain political power in proportion to their numbers.

In the United States, the "one person, one vote" principle was established in a series of cases in the 1960s. Applying the Equal Protection Clause of the United States Constitution, the Supreme Court majority opinion in Reynolds v. Sims (1964) ruled that state legislatures needed to redistrict in order to have congressional districts with roughly equal represented populations. In addition, the court ruled that, unlike the United States Congress, both houses of state legislatures needed to have representation based on districts containing roughly equal populations, with redistricting as needed after censuses.

The British trade unionist George Howell used the phrase "one man, one vote" in political pamphlets in 1880.

This phrase was traditionally used in the context of demands for suffrage reform. Historically the emphasis within the House of Commons was on representing areas: counties, boroughs and, later on, universities. The entitlement to vote for the Members of Parliament representing the constituencies varied widely, with different qualifications over time, such as owning property of a certain value, holding an apprenticeship, qualifying for paying the local-government rates, or holding a degree from the university in question. Those who qualified for the vote in more than one constituency were entitled to vote in each constituency, while many adults did not qualify for the vote at all. Plural voting was also present in local government, whereby the owners of business property qualified for votes in the relevant wards.

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