There should be tighter controls on allowing a rape victim's previous sexual history or their sexual "disposition" to be admitted as evidence in court, the Government has been told.
And a victim's sexual "reputation" should be completely off-limits, the commission said in its review of the Evidence Act, released today.
Law Commission president Sir Douglas White said the review found that the act was generally working well but could go further to assist victims of sexual and family violence.
"Our consultation highlighted that the process of giving evidence can be particularly stressful for complainants in sexual and family violence cases," he said.
"Our review has also shown there is a risk of jurors being affected by myths and misconceptions about sexual and family violence.
"We are therefore recommending a number of improvements to the rules of evidence in sexual and family violence cases."
In sexual violence cases, a complainant's sexual history with any person other than the defendant is already inadmissible - unless the judge decides it would be contrary to the interests of justice to exclude it.
The commission now wants the complainant's past sexual history with the defendant themselves to also meet this high threshold. Though the court should still be able to hear the simple fact that the complainant was in a sexual relationship with the defendant, the commission said.
Any evidence about a sexual violence victim's sexual disposition should also only be admissible with the judge's permission, the report said. And any evidence of a victim's "reputation for having a particular sexual disposition" should be inadmissible.
In family violence cases, the commission said complainants should be able to record their evidence - including cross-examination - in advance of the trial and have the video played at hearing.
Judges should be required to intervene when questioning of a witness was unacceptable. And guidelines should be developed for juries to address myths and misconceptions around sexual and family violence cases.
The daunting court process has previously been cited as a factor in the low rate of convictions for sexual violence in New Zealand.
The Law Commission review also made recommendations to promote greater recognition of tikanga Maori in court procedures, and to ensure that defendants' rights to a fair trial were preserved.
Justice Minister Andrew Little said he had received the report and would table it in Parliament today.
"I am looking forward to considering the recommendations for change and working through them in more detail," he said.