The court upheld the 16-year jail sentence on Thursday, with a non-parole period of 10 years, imposed on Massey for the murder of Elizabeth Booshand.

Massey was found guilty of the murder by an ACT Supreme Court jury after a month-long trial in 2011.

But her lawyers appealed the conviction, arguing Justice Malcolm Gray misdirected the jury at the end.

Director of Public Prosecutions Jon White disagreed, arguing there was no fault in the trial judge's final directions to the jurors.

Tensions between Massey and Ms Booshand erupted in July 2008 when the pair clashed outside a chicken shop in Charnwood.

There was a confrontation outside the shop and the pair continued the clash in an adjacent alley.

Ms Booshand was fatally stabbed in that alley, but Massey's lawyers maintained their client acted in self-defence and never meant to kill.

Massey's legal team appealed the conviction on four grounds.

Three grounds related to the directions Justice Gray gave the jury about the law of self-defence.

The fourth ground for appeal concerned the question of intent.

Chief Justice Terence Higgins, Justice Richard Refshauge and Justice Steven Rares heard the appeal in May last year.

At the hearing, barrister Jack Pappas argued the directions on self-defence took the matter out of the hands of the jury. ''If Massey started the fight with the deceased or willingly engaged in it, she cannot claim to defend herself in a counter attack unless her original aggression had ended at the time of the counter attack,'' Justice Gray said at the trial.

''If she had ended her aggression, but was then required to defend herself against a new attack, the law allows her to raise self-defence.''

Mr White argued the judges needed to consider the broader evidence put before the jury. He said there was evidence of the background animosity, relative ages and health, and previous threats uttered by Massey towards Ms Booshand.

All three judges dismissed the appeal and Justice Refshauge published the decision on Thursday.

On the question of self-defence, the ACT Court of Appeal judges found witness evidence varied, making the altercation difficult to summarise for Justice Gray.

"The trial judge's directions were expressed in a practical way that set the question of self-defence into the factual context in which it could arise," the three judges wrote.

"Hence the trial judge's introduction to the impugned part of his charge invited the jury to consider whether the appellant started the fight or willingly engaged in it. The appellant seized on the first of those alternatives and ignored the second in criticising the summing up."

On the question of intent, they found the trial judge's direction actually favoured Massey.

"The trial judge identified the factual matters to which the jury had been taken by counsel," they wrote.

"He reminded them of the appellant's denial of forming any intent to kill or cause grievous bodily harm and her assertion that she had not been aiming for any particular part of the body when she stabbed the deceased.

"There is no substance in this ground, which, in any event, was only faintly pressed in oral argument."