Requirement to issue reasoned decision in the last instance

Electoral Act 1968, 121(f)

Trial of election petitions

at the conclusion of the trial of any electionpetition, the High Court shall determine whether the respondent was dulyelected or whether any, and if so what, person other thanthe respondent was or is entitled to be declared duly elected;

http://aceproject.org/regions-en/eisa/BW/Electoral%20Act%201968.pdf