A New Zealand High Court judge said the man who was accused of assaulting two female German tourists was acquitted because the women were foolish enough to walk the streets of Auckland "dress as they were."

The High Court's Justice John Priestly said he was surprised by the jury's acquittal decision. His comments have sparked outrage from advocates who sided with the victims.

Tony Clement, 29, was found guilty by the jury for the charge of aggravated robbery of two girls in Sept 2012 at Albert Park. However, the same jury acquitted the man of threatening to kill and indecent assault.

When Mr Clements was sentenced to jail for three years and 10 months, the judge addressed the decision of the jury. He said the defence panel and the Crown, including his summary, all agree in the facts presented regarding the case. The facts refer to the evidence and victims' credibility.

He addressed Mr Clements during sentencing and said he was surprised with the jury's decision to clear him of the indecent assault charge and threatening to kill.

The Justice said, "My conclusion is that.... a combination of the foolishness of your victims, venturing out alone at night in a park in a strange city, dressed as they were, and the total absence of any DNA evidence, led to the jury collectively entertaining a reasonable doubt on the two indecent assault charges."

Barrister Catriona MacLennan interpreted the judge's statement as implying that the 18-year-old German tourists brought the crime upon themselves, being "dressed as they were." In other words, they placed themselves in a position to be attacked by people like the accused.

Ms MacLennan said the judge was implying a lesson that if a woman was attacked late at night and without a male companion, it was her fault if she was attacked. She was shocked to hear the judge's statements and said there was no connection to the attack and what the women wore that night. She said there was no reason for women to remain locked inside their homes at night.

Ruth Money, a spokesperson for Sensible Sentencing Trust, said the judge made a poor choice in words. She said it was difficult enough for victims to report sexual assault crimes and then to appear in court to seek justice.

Blaming the victims was common, according to Dr Kim McGregor, a Rape Prevention Education executive director. Ms McGregor said the judge's comments only indicate how victim-blaming has become a widespread practice.

She said the focus of sex attacks should be on the perpetrator and not the victims. Questions like, "Why was he carrying a knife?" , should be addressed first. She also wanted to know why the perpetrator seemed to be waiting for his chance to terrorise the girls.

A spokesperson for the judiciary, Neill Billington, said that the judge's remarks were meant to explain how the jury might have interpreted the evidence and their reasons why they acquitted the perpetrator.

He said the comments did not reflect the judge's personal opinion on the matter was "attempting to explain an apparently inconsistent verdict."