Outrage over the use of Grace Millane's sexual history in defence of her killer

Protesters rode to Parliament on Monday for a day they wish didn't need to exist - the International Day for the Elimination of Violence against Women.

Marches for White Ribbon - an organisation which campaigns to end violence against women - were held across the world on Monday in Paris, Rome and Brussels.

The Wellington White Ribbon Day protest came amid outrage that the lawyers defending Grace Millane's murderer raised her sexual history and preferences.

"Some of that seemed tangential at best, and irrelevant to what the issues were in this case," said Steph Dyhrberg from Wellington Women's Lawyers' Association.

But as society changes, so do laws. 

Tuesday marks 10 years since the defence of provocation was abolished following public outrage that a man used it as his defence for murdering Sophie Elliott.

An incoming law aims to reduce the trauma sexual violence victims' face in court by enabling judges to stop distressing question lines.

 Dyhrberg says it could expand to cover murder trials.

"I think it fits into the picture of gendered violence, and that would be a potential way of looking at it." 

But the Justice Minister says he doesn't think it's possible to stop historical sexual information being raised as part of a murder defence.

"The Bill we have drafted does not go that far, and I'm not sure how we could make it go that far," said Justice Minister Andrew Little.

He says people shouldn't have limitations put on what they can argue in defence, as they need to be able to challenge allegations.

"And effectively put their case, as uncomfortable as that may be, as foul as some of that evidence may be," Little told Newshub.

But regardless of legality, sexual history could cease to be raised if doing so becomes socially unacceptable.

"It would have to influence the way lawyers, judges, prosecutors, everyone, behaves in hearings," said Dyhrberg.

That's why societal change is the focus for White Ribbon.