A man who claimed he reasonably acted in self-defence when he bashed his girlfriend's ex-lover to death has been denied a High Court appeal against his murder conviction.
Mark Vincent Dayney, then 35, was found guilty by a jury in December 2021 of murdering Mark Emanuel Spencer in the Gold Coast suburb of Coomera.
Mr Spencer was attacked in his own home with a baseball bat and tennis racquet in the early hours of October 1, 2014.
The High Court on Wednesday dismissed Dayney's appeal against a decision by the Queensland Court of Appeal that had dismissed his second attempt to overturn his conviction.
Dayney had argued that a section of Queensland's criminal code concerning self-defence against provoked assault should have allowed him to be acquitted of murder.
High Court Chief Justice Stephen Gageler and four other justices found that Dayney had instigated the confrontation with Mr Spencer and was therefore required to attempt to retreat from the conflict before using deadly force.
"(Queensland law) requires that (the accused) interrupt or remove, as far as is practicable, their role in inciting the conflict and thereby their blameworthiness," Chief Justice Gageler stated.
A Queensland jury in 2021 heard Dayney's girlfriend was a sex worker who paid for the couple's drug habits and he became enraged when he discovered Mr Spencer attempting to resume their prior relationship with her through an escort booking.
Dayney told his girlfriend to attend Mr Spencer's house and create a distraction while he would break in and steal any money or methamphetamine he could find.
Instead of going through with his part of the plan, Dayney confronted the pair in the living room and hit Mr Spencer before wrestling with him.
Dayney had testified Mr Spencer pulled out a gun immediately when entering a lounge room and everything he did after that was to save his own life or that of his girlfriend who was present.
Dayney was jailed for life in 2021 after he had already spent more than three-and-a-half years on remand.
