The 51st New Zealand Parliament was elected at the 2014 general election. This Parliament consists of 121 members (120 seats plus one overhang seat) and will be in place from September 2014 until the New Zealand general election, 2017. Following the final vote count John Key was able to continue to lead the Fifth National Government.
The Parliament was elected using a mixed-member proportional representation (MMP) voting system. Members of Parliament (MPs) represent 71 geographical electorates: 16 in the South Island, 48 in the North Island and 7 Māori electorates. The remaining members were elected from party lists using the Sainte-Laguë method to realise proportionality. The number of geographical electorates was increased from 70 at the previous election, to account for New Zealand's increasing population.
The Representation Commission is tasked with reviewing electorate boundaries every five years following each New Zealand census. The last review was undertaken in 2007 following the 2006 census, and the electorate boundaries determined then were used in both the 2008 and 2011 general elections.
The next census was scheduled for 8 March 2011, but it was postponed due to the disruption caused by the 2011 Christchurch earthquake on 22 February . The census was formally conducted on 5 March 2013 with additional data collection over the following several weeks, Following the census it was determined there would be sufficient time to conduct a boundary review of all electorates.
The boundaries were redrawn based on population distribution and the Māori electoral option, where people of Māori descent can opt to be either on the general or the Māori roll. By law, the South Island must have 16 general electorates, with the number of North Island general and Māori electorates being the respective population in each group divided by one-sixteenth of the South Island general electorate population, within a tolerance of five percent. At the 2011 election, there were 47 North Island general electorates and seven Māori electorates, totalling 70 electorates across the country.
Following significant consultation final boundaries were released by the Representation Commission on 17 April 2014. The 2014 general election was conducted under these boundaries on 20 September 2014. The increase in population in the Auckland region as recorded in the 2013 census meant an extra electorate was required to keep all electorates within five percent of their quota. To accommodate an extra electorate the Electoral Commission proposed major changes in west Auckland by abolishing the Waitakere electorate and establishing two new electorates, namely Kelston and Upper Harbour. Boundaries within Christchurch changed substantially, with several electorates growing and decreasing due to population movement around the city since the 2010–11 Christchurch earthquakes. In particular a dramatic change was seen in the electorates of Christchurch East, Christchurch Central and Port Hills with lesser changes in Selwyn, Wigram and Waimakariri.
The tables below show the members of the 51st Parliament based on preliminary counts of the 2014 general election.
The National Party won 47.04% of the vote, entitling it to 60 seats. As it won 41 electorates, an additional 19 members were taken from the party list. After the resignation of Northland MP Mike Sabin a by-election was held and lost to New Zealand First. The party's share of seats was reduced to 59.
15 new National Party members were elected, nine from electorates and six from the list. 45 members from the 50th Parliament were returned.
The Labour Party won 25.13% of the vote, entitling it to 32 seats. As it won 27 electorates, an additional 5 members were taken from the party list. After the resignation of David Shearer in 2017, the party's share of seats was reduced to 31.
Three new Labour Party members were elected from the list. 29 members from the 50th Parliament were returned.
The Green Party won 10.7% of the vote, entitling it to 14 seats. As it did not win any electorate, all members were taken from the party list.
One new Green Party members were elected, with thirteen members from the 50th Parliament returning.
New Zealand First won 8.66% of the vote, entitling it to eleven seats from the party list. An additional seat was gained for the party when Winston Peters won the Northland by-election.
The Māori Party won 1.32% of the vote, which is short of the 5% threshold. However, the Māori Party won an electorate and will thus be represented by one electorate MP. The 1.32% party vote share entitles the party to two seats, including an MP from the party list.
United Future won 0.22% of the vote, which is short of the 5% threshold. United Future won one electorate and will thus be represented by one electorate MP. Because the 0.22% party vote share would not entitle United Future to any seats, the size of the 51st Parliament was increased to 121 seats.
ACT New Zealand won 0.69% of the vote, which is short of the 5% threshold. ACT won one electorate and was thus represented by one electorate MP. The 0.69% party vote share entitled the party to one seat.
In January 2015, National's Mike Sabin resigned for personal reasons following reports he was the suspect of a police investigation, forcing a by-election in the Northland electorate. The by-election was won by the New Zealand First candidate, Winston Peters. As Peters was already a list MP, this resulted in the election of Ria Bond.
In October 2015, Russel Norman resigned to take up a position as the Chief Executive of Greenpeace Aotearoa New Zealand, and was replaced as a Green Party list MP by Marama Davidson.
In December 2015, Tim Groser resigned to become the New Zealand Ambassador to the United States, and was replaced as a National Party list MP by Maureen Pugh.
In October 2016, Kevin Hague resigned to take up a position as Chief Executive of the Royal Forest and Bird Protection Society of New Zealand, and was replaced as a Green Party MP by Barry Coates.
In October 2016, Labour's Phil Goff resigned to take up his new elected position of Mayor of Auckland, forcing a by-election in the Mount Roskill electorate. The by-election was won by the Labour Party candidate, Michael Wood.
In December 2016, Labour's David Shearer resigned to take up a role with the United Nations, forcing a by-election in the Mount Albert electorate. The by-election was won by Labour Party List MP Jacinda Ardern.