The Electoral (Integrity) Amendment Acts are two Acts of Parliament by the New Zealand Parliament which force the expulsion of members of the New Zealand Parliament who have resigned from or been expelled from the political party for which they were elected. Two such Acts have been passed: the Electoral (Integrity) Amendment Act 2001 (see § 2001), which expired in 2005, and the Electoral (Integrity) Amendment Act 2018 (see § 2018), which remains in force.

The New Zealand Parliament is elected using mixed-member proportional voting and the Electoral Act 1993 provides for the election of list members on behalf of registered political parties. Particularly in the 1990s, repeated instances of party switching led to criticisms that the proportionality of parliament as determined at a general election had been disturbed. The Electoral (Integrity) Amendment Acts were therefore attempts by the legislature to control its members' affiliations and votes in a way that conformed to the most recent election outcome. The New Zealand political parlance of "waka-jumping" has given rise to the colloquial description of the Acts as the "waka-jumping laws."

The Acts operate differently depending on whether the expelled member represents an electoral district or if they were elected on a party list. The expulsion of an electorate member triggers a by-election; expelled list members are simply replaced by the next available candidate from their former party's list. In either instance, the Speaker of the House must make a declaration expelling the member. To date, two such declarations have been made. Former ACT MP Donna Awatere Huata was expelled in 2004 under the 2001 Act, while former Green MP Darleen Tana was expelled in 2024 under the 2018 Act. Despite the Acts being in force, other members and parties have conducted political manoeuvres to enable them to change parties or to be political independents without being expelled.

The current law, the Electoral (Integrity) Amendment Act 2018, inserted six new clauses into the Electoral Act 1993. Section 55A states that the seat of a Member of Parliament (MP) becomes vacant when they cease to be a parliamentary member of the political party for which they were elected. This is considered to have occurred in either of the following scenarios:

The provisions of the Electoral Act 1993 which concern vacancies apply. Electorate MPs are replaced through a by-election (section 129). List MPs are replaced by the first available member on their original party's list (section 134).

The two Electoral (Integrity) Amendment Acts feature some minor drafting differences. In addition, the 2001 Act included a sunset clause so that it would automatically expire at the 2005 general election. Such a clause was not included in the current version of the legislation.

Since New Zealand adopted proportional representation ahead of its 1996 general election, party switching (or waka-jumping) had been criticised for disturbing the proportionality of parliament as determined at a general election. Previously, party dissidents had simply served as independents. However, in the 44th Parliament (from 1993 to 1996) and 45th Parliament (1996 to 1999), 22 MPs defected to other parties. The Alliance, a party which had been formed by Jim Anderton's defection from Labour to NewLabour in 1989 and had been disadvantaged by the defection of Alamein Kopu in 1997, supported tighter controls on party switching. The Labour Party was also in favour. Deputy leader Michael Cullen introduced legislation to forcibly expel party switching members in October 1997, but a 5–5 split on the electoral law committee prevented the bill from progressing further.

The two parties jointly campaigned at the 1999 election for tighter controls on party switching which were soon progressed by the new Labour–Alliance coalition government. In the 1999 Speech from the Throne, the Governor-General announced on behalf of the new government: