In Canadian politics as usual a hatchetman is a journalist or columnist who is nominally neutral in an election, and may switch political spots between elections, but during elections remains focused on publicizing negative "facts" and systematically devoting energy to negative campaigning against a particular candidate, to ensure that candidate cannot stay on-message but must devote time to responding to this.

A hatchetman who runs for the office himself in order to carry this disruption into all-candidates meetings and other debates and create partisan material becomes a mad dog - but then loses the appearance of neutrality and is subject to campaign finance limits. While small parties may rely more on mad dogs, big ones hire hatchetmen.