A man jailed for three years for a machete attack that severely injured two brothers has had an appeal bid thrown out of court.

Kenneth Caines was sentenced last December following an assault that left one of the brothers coughing up blood and fearing for his life after he was slashed in the head.

The other brother ? who had his hand sliced in the ordeal ? was forced to give up his job as a bus driver because of the injury.

A jury found Caines guilty of unlawfully wounding Marlon Rewan. The 20-year-old defendant was also convicted of two counts of wounding with intent, against both Marlon and Stevon Rewan.

And now an appeal against those convictions has been dismissed after a Court of Appeal hearing last month.

The trial had heard how Marlon was knocked unconscious by the defendant and another teen, before being robbed of $3,000 and jewellery outside a Hamilton bar.

Marlon and his two brothers, Stevon and Devon, went to the Devonshire house of the teenager they held partly responsible for the robbery in an attempt to get back the stolen haul.

There they encountered Caines, armed with a machete. As tempers flared, he lashed out.

The court heard Devon was struck on the hand as he tried to protect himself with a four-foot wooden pole. Stevon was cut across the head in a blow he said went "straight to my skull".

Elizabeth Christopher, lawyer for Caines, argued in the Court of Appeal that the trial judge had made a mistake in failing to leave the issue of provocation to the jury in relation to the three counts.

But the appeal judges, pointing to the severity of the injuries suffered by the brothers, ruled: "On the basis of the evidence for the prosecution there was no provocation which could justify the two (wounding with intent) assaults...

"It is not surprising, therefore, that the learned trial judge informed counsel of her intention to withdraw provocation as a defence worthy of the jury's consideration."

The appeal judges said that they could not agree with Ms Christopher's submission that the manner in which Caines used the machete was unlikely to cause death or grievous bodily harm. "It was not only likely to but in fact caused very serious injuries," their ruling added.

They said an argument could be made that the defendant had put forward a version of events which, if believed by the jury, could give him a provocation defence.

But they added: "The difficulty with that argument is that the appellant was so discredited by cross-examination that his version of events did not bear close scrutiny."

The defence also claimed in the appeal hearing that the trial judge made a mistake by leaving the jury with the impression that she "favoured the prosecution side rather than the defence".

Ms Christopher pointed to a comment by the judge in which she said the jury should ask themselves if Caines, of Curving Avenue, punched Marlon in retaliation for a kick or "if it was a young man who just wanted to fight when he knew he had an unfair advantage", because he had a friend with him.

The appeal judges, rejecting this complaint, one of seven rejected in total, said that a "robust expression of view" was not necessarily unfair. The trial judge had also warned the jury that matters of fact were entirely their concern.

Ms Christopher also claimed that when summing up the evidence the trial judge "made excuses" for the brothers' attempts to confuse their role in the events on the day of the attack.

However, the Appeals Court ruled the trial judge gave correct directions and added: "The issue throughout was one of credibility.

"The jury clearly believed the evidence of the Rewans and disbelieved that of the appellant where there was a conflict."