Accused rapists who plan to argue that sex with their victims was consensual may have to prove in court what measures they took to gain consent.
The proposal is one of three changes to sexual violence legislation being put forward by the Justice Ministry.
"Changing the law would send an important message about community standards and about what the law expects," ministry documents say.
"In particular, there would be a reminder that consent has to be obtained on each separate occasion."
Under the proposal, if a defendant claimed sex was consensual the courts would have to look at what steps had been taken to find out that consent had been given.
Other changes being considered are including creating a legal definition of consent to remove ambiguity and banning questioning complainants about their sexual history with the alleged attacker.
The ministry has issued a discussion paper on the proposals and is calling for public submissions.
Nineteen per cent of women and 5 per cent of men would be subjected to sexual violence at some point in their lives, but it was thought about 90 per cent of sexual offending went unreported, the ministry said.
"Victims and the public need to see that sexual violence is taken seriously, that justice is being done, and that this behaviour is not tolerated in our society."
The discussion document only relates to issues affecting sexual violence between adults.
Sexual offending against children is being addressed by a separate ministry task force.
Bill Hodge, Auckland University associate professor of law, said though he was "not one to stick up for criminals", caution was needed when making changes to legislation.
Requiring a higher standard of proof of consent from defendants would lessen the burden on the Crown to prove an offence.
"So just because it is hard to get convictions we do away with the standards? A drunk consent is still consent," Dr Hodge said.
Helen Sullivan, Wellington Sexual Abuse Help Foundation general manager, said the changes would be an important first step in improving attitudes to sex crimes and creating clearer guidelines about acceptable behaviour.
"Society perceives that there is a whole bunch of vindictive women out there waiting to get back at guys."
Balancing the rights of both the accused and the victim was a "tricky area" but more needed to be done to strengthen victims' rights, Ms Sullivan said.
Justice Minister Annette King said that though legislation changes on their own would not automatically lead to an increase in convictions, they were an "important first step".
The aim of the document was to create discussion within the community about how to deal with sexual violence.
The document raised questions about sexual violence, Ms King said. "What are the boundaries of acceptable sexual conduct in law, and what aspects of the current law may act as barriers to cases proceeding through the justice system or inhibit successful convictions?"
- The Dominion Post