By-elections are held for the Parliament of Nauru to fill vacancies that occur between general elections.
Previously, Nauruan general elections and by-elections used different voting systems. Nauru uses the unique Dowdall system for general elections, but for by-elections it used a more conventional preferential system. Candidates had to receive an absolute majority of first preference votes. If none did, then the candidate with the fewest first preference votes was eliminated, and the next preference votes on their ballots were distributed to the remaining candidates. This cycle continued until one candidate had an absolute majority of votes.
A previous version of the Electoral Act in force in 2012, under the section entitled "Counting of votes in election", differentiates the methods of counting votes in a general election and by-election. The section entitled "Counting of votes in election" in the current Electoral Act applies the same vote counting method for every election in Nauru.
A writ was issued by the speaker of Parliament on 29 June 1971 to fill a vacancy in the Ubenide Constituency. The election was held on 14 August. The winner was determined after the four count of preferences.
A writ was issued by the acting speaker of Parliament on 20 April 1972 to fill a vacancy in the Yaren Constituency. The election was held on 3 June. The winner was determined after the fifth count of preferences.
A writ was issued by the speaker of Parliament on 20 July 1976 to fill a vacancy in the Yaren Constituency. The election was held on 28 August.
A by-election was triggered in the Aiwo Constituency when Speaker Edwin Tsitsi resigned as MP in December 1976. The election was held on 5 February 1977.
MP Austin Bernicke died in January 1977. A writ was issued by the speaker of Parliament on 17 January 1977 to fill a vacancy in the Buada Constituency. The election was held on 5 March.
A writ was issued by the speaker of Parliament on 11 February 1977 to fill a vacancy in the Anetan Constituency. The election was held on 19 March.
A writ was issued by the speaker of Parliament on 7 March 1977 to fill a vacancy in the Aiwo Constituency. MP René Harris lost his seat due to being convicted by a court of assault. The election was initially scheduled for 16 April, but it was deferred by a court judgment. By 9 May, the election was rescheduled for 4 June. The election was held on 4 June. Harris was re-elected.
A writ was issued by the speaker of Parliament on 20 September 1978 to fill a vacancy in the Ubenide Constituency. The election was held on 21 October.
A writ was issued by the speaker of Parliament on 6 February 1979 to fill a vacancy in the Aiwo Constituency. The election was held on 10 March.
A writ was issued by the speaker of Parliament on 10 June 1981 to fill a vacancy in the Aiwo Constituency. MP René Harris resigned and ran in the resulting by-election as a way to test whether the voters of his constituency supported him. The election was held on 18 July. Harris was re-elected.
Speaker David Peter Gadaraoa resigned from parliament in September 1981. A writ was issued by the new speaker of Parliament, Reuben Kun, on 18 September 1981 to fill a vacancy in the Anabar Constituency. The election was held on 24 October.
MP Joseph Detsimea Audoa died on 18 April 1984. A writ was issued by the speaker of Parliament on 25 April 1984 to fill a vacancy in the Yaren Constituency. The election was held on 26 May.
MP James Ategan Bop died on 12 July 1984. A writ was issued by the speaker of Parliament on 23 July 1984 to fill a vacancy in the Meneng Constituency. The election was held on 25 August.
A writ was issued by the speaker of Parliament on 29 July 1988 to fill a vacancy in the Ubenide Constituency. The election was held on 25 August.
MP Kenas Aroi died on 22 January 1991. A writ was issued by the speaker of Parliament on 28 January 1991 to fill a vacancy in the Boe Constituency. The election was held on 2 March.
MP Hammer DeRoburt died on 15 July 1992. A writ was issued by the speaker of Parliament on 27 July 1992 to fill a vacancy in the Boe Constituency. The election was held on 22 August.
A writ was issued by the speaker of Parliament on 13 June 1994 to fill a vacancy in the Ubenide Constituency. The election was held on 9 July.
A writ was issued by the speaker of Parliament on 28 June 1996 to fill a vacancy in the Buada Constituency. The election was held on 9 July.
MP Roy Degoregore died on 24 August 1996. A writ was issued by the speaker of Parliament on 2 September 1996 to fill a vacancy in the Anetan Constituency. The election was held on 5 October.
In early 1998, five Nauruan MPs were dismissed by Speaker Kennan Adeang. As a result, a writ was issued by the speaker of Parliament on 22 January 1998 to fill a vacancy in the following constituencies: Boe, Buada, Meneng, Ubenide, and Yaren. The elections were held on 21 February. Three of the five dismissed MPs were re-elected.
A writ was issued by the speaker of Parliament on 24 June 1998 to fill a vacancy in the Aiwo Constituency. The election was held on 25 July.
A writ was issued by the speaker of Parliament on 7 November 2001 to fill a vacancy in the Ubenide Constituency. The election was held on 8 December.
Speaker Vassal Gadoengin died on 15 December 2004. A writ was issued by the speaker of Parliament on 24 December 2004 to fill a vacancy in the Anetan Constituency. The election was held on 22 January.
MP Valdon Dowiyogo's death triggered a by-election. A writ was issued by the speaker of Parliament on 22 December 2016 to fill a vacancy in the Ubenide Constituency. The election was held on 19 January 2017. A report from the Nauru Electoral Commission noted that, given the amount of time since the last by-election in Nauru, some voters were confused by the preferential system used as opposed to the Dowdall system used in general elections. The MP who was elected, Gabrissa Hartman, was the third woman elected to the Parliament of Nauru.
MP Jaden Dogireiy's court conviction and subsequent disqualification from parliament triggered a by-election. A writ was issued by the speaker of Parliament on 1 May 2019 to fill a vacancy in the Anabar Constituency. The election was held on 30 May. Due to how close the results between candidates Ludwig Scotty and Pyon Deiye were, a recount was triggered. The election used the Dowdall system of voting.