By-elections in New Zealand occur to fill vacant seats in the New Zealand Parliament. The death, resignation, or expulsion of a sitting electorate MP can cause a by-election. (Note that list MPs do not have geographic districts for the purpose of provoking by-elections — if a list MP's seat becomes vacant, the next person on his or her party's list fills the position.)

A by-election need not take place if a general election will occur within six months of an electorate seat becoming vacant. In 1996 the general election date was brought forward slightly, to 12 October, to avoid a by-election after the resignation of Michael Laws.

In recent years by-elections have not occurred particularly frequently — only one in the 2002 - 2005 parliamentary term, and none in the 1999 - 2002 term. This is because most MPs who retire mid-term (most recently Labour MP Jim Sutton) are List MPs, and are simply replaced by the next member on their party list.

Historically, however, they have taken place considerably more frequently — the 2nd Parliament of 1856 - 1860, for example, saw at least twenty by-elections, despite the House of Representatives then having only thirty-seven seats.

In the past it was not uncommon for an MP who died in office to be replaced with an immediate family member such as a brother, wife or son. This resulted in the election of the first woman MP Elizabeth McCombs (who was in turn succeeded by her son Terence McCombs) and the first woman National MP Mary Grigg; both of whom took over their husband's seat. This practice has however fallen out of favour since the 1970s.

List of New Zealand by-elections

The following incomplete table lists previous by-elections in New Zealand. Interestingly, it features the names of ten subsequent Prime Ministers (#).

See also

• New Zealand elections
• Elections in New Zealand

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