Conscience vote

In western democracies, especially Australia, the elected members of the parliament are generally required to vote in single party blocs. That is, they must conform with the opinion of the entire political party. Those members who do not, face expulsion from their respective parties.

On rare occasions however, an issue is either very contentious, or a subject on which the major parties have no official stance. The members are then allowed to vote with their 'conscience'