A substitute is a political candidate who is not directly elected, but who succeeds a politician holding an elected office after that person ceases to hold the office due to, for example, resignation or death. This system can be used to fill casual vacancies instead of holding by-elections or special elections to fill the vacant office. Substitutes are nominated, not at the time the vacancy arises but, rather, before the election for the information of voters. In voting systems which use electoral lists, the candidates on a given list who are not among those initially elected may become the substitutes for those who are. In other systems, individual candidates may have substitutes.
Belgium
In Belgian federal parliamentary elections, each electoral list has both a list of "effective" candidates and a list of "substitutes" (Dutch: opvolgers; French: suppléants). The system was introduced as part of the law of 29 December 1899 introducing proportional representation. Before that, by-elections were held to succeed members.
For municipal and provincial elections, as well as those for the Parliament of the Brussels-Capital Region since 2019, there is only one list, and substitutes are designated, according to various systems from one region to another, on the base of their own preferential votes, weighted or not with list votes, i.e. not for one or several specific candidate(s).
France
In the elections for the French National Assembly, each candidate is on a ticket with a substitute (French: Suppléant), who assumes the functions of the elected deputy under specific conditions. The substitute assumes the functions of the deputy if the deputy dies, enters the executive government, is appointed by the Government to an assignment of more than six months' duration, or appointed to the Constitutional Council or Defender of Rights (Défenseur des droits).[1]
If the deputy resigns, or their election is determined to be invalid, a by-election (French: élections legislatives partielles) is held instead.
In the Philippines, a substitute is a person who replaces the candidate up to midday of election day. The Commission on Elections only allows substution for certain reasons and on certain periods, if the original candidate dies, withdraws or is disqualified; after a certain date, substitution via withdrawal is prohibited, and a candidate can only be substituted by someone who has the same surname as the original candidate. Furthermore, only candidates who were nominated by a political party can be substituted.[9]
If a vacancy occurs after the term of office begins, substitutes do not replace the original candidate:
For executive offices (president, governor, mayor), the deputy (vice president, vice governor, vice mayor, as the case may be) replaces the original officeholder
For the vice president, the president nominates a new officeholder, which is then confirmed by Congress.
For members of Congress, a special election (called as "by-elections" elsewhere) is held, except for members elected under the party-list system, where the next person on the list takes their place.
For deputies of local executive offices (vice governor, vice mayor), the candidate with the highest number of votes in the local legislature (Sangguniang Panlalawigan and Sangguniang Panlungsod or Sangguniang Bayan, as the case may be) replaces the original officeholder
For members of local legislatures, the political party nominates a new officeholder; if the vacating officeholder is an independent, the chief executive (president, governor, mayor, as the case may be) appoints a replacement.