Explainer: What makes a by-election necessary in Malaysia, and when it is not?

A by-election in Malaysia is held when a seat becomes vacant due to reasons other than the dissolution of Parliament. This can occur if an incumbent resigns, gets expelled, passes away, or is disqualified from holding office. However, by-elections are not triggered in cases where the MP is of unsound mind, an undischarged bankrupt, fails to declare election expenses, misses consecutive sittings of the Dewan Rakyat or State Legislative Assembly, becomes a citizen of another country, or is a member of both Dewan Rakyat and Dewan Negara.

Additionally, switching political parties is now considered a disqualification due to Article 49A, also known as the anti-party hopping law, introduced in 2022. Resignations do not automatically lead to a by-election, with exceptions being when the vacancy occurs within two years before the natural dissolution of Parliament or when the vacancy does not impact the numerical strength of the party with a majority in the Dewan Rakyat, as seen in the unity government led by Pakatan Harapan controlling two-thirds of the parliament.