The most widely accepted rule for redistricting is that districts should be relatively equal in population. This is because representation by population is a central tenet of democracy, and, in countries that employ single-member districts, this rule translates into the principle of equal populations across districts. Equally populous districts are necessary if voters are to have an equally weighted voice in the election of representatives. If, for example, a representative is elected from a district that has twice as many voters as another district, voters in the larger district will have half as much influence as voters in the smaller district.
The degree to which countries demand population equality varies. The United States is unique in its adherence to the doctrine of equal population. No other country requires deviations as minimal as the 'one person, one vote' standard that has been imposed by U.S. courts since the early 1960s. New Zealand comes closest to that strict standard, but deviations of up to five percent from the electoral quota are permitted.
In Australia, federal electoral districts must fall within 10 percent of a state's electoral quota, as forecast by population projections three and one-half years into the future. Australia aims for equality of population halfway through its seven-year redistricting cycle to avoid wide discrepancies at the end of the cycle. Australia's close attention to population equality is relatively recent. Thirty years ago, the practice of heavy rural loading--creating rural districts that were much smaller in population than urban districts--was quite common. (For more information on Australian redistricting practices, see the case study on Australia, Federal Redistribution in Australia.)
In Canada, the independent commissions charged with creating federal electoral districts are allowed to deviate by up to 25 percent from the provincial quotas. But since 1986, commissions have been permitted to exceed the 25 percent limit under 'extraordinary circumstances.' This provision was used to create five of the 295 seats in the Canadian House of Commons in 1987, and two of 301 seats in 1996. In 1996, one Quebec seat was created with a population 40.2 percent below the provincial average, and one Newfoundland district was created with a population 62.5 percent below the provincial average. (For more information on Canadian redistribution, see the case study on Canada, Representation in the Canadian Parliament.)
In Germany, as in Canada, districts are not to deviate from the electoral quota by more than 25 percent. It is not until a district deviates by more than 33 percent, however, that the law requires that a district be redrawn. The German legislature, which must approve any proposed federal redistricting plan before it can be implemented, often refrains from adopting district modifications recommended by the Electoral Districts Commission until a district deviates by 33 percent or more.
The United Kingdom allows even larger deviations in district populations. The original standard was set at 25 percent in 1944. But the standard was repealed only two years later. The current rule requires that constituencies be 'as equal as possible,' but this rule must be balanced against the principle of respect for local boundaries as much as possible. Equally populous districts can also be disregarded for 'special geographic circumstances.' Allowances for natural communities prompted English boundary commissioners in 1983 to leave the Isle of Wight with 95,000 electors as a single constituency, while respect for local London boundaries left suburban Surbiton with only 48,000 electors. Likewise, recognising the difficulties of island travel, the commissioners in Scotland granted the Western Isles (population 24,000) and Orkney and Shetland (population 31,000) their own representatives.
The degree to which a country adheres to strict equality of population is related to the significance attached to individual political equality. The United States is strongly committed to individual rights and equality, so perhaps it is not surprising that it developed the strictest population deviation standards of any country using single-member districts. Other countries, while recognising the importance of population equality, have chosen to balance this factor against other redistricting criteria perceived as equally valid. In the United Kingdom, respect for local administrative boundaries is given precedence over exact equality of number. In many African countries, the need to recognise individual tribes may take precedence over population equality. Each country must determine how much variation from the ideal of exact population equality will be tolerated to accommodate other redistricting goals.
