Debate on whether people with mental health conditions should be required to actively seek consent has continued as NSW parliament considers an overhaul of sexual assault laws.
The draft law creates a requirement of 'affirmative consent' - meaning people have to say or do something to find out whether their partner consents to a sexual activity, or they could be guilty of sexual assault.
The bill says the affirmative consent requirement does not apply if a person accused of sexual assault was suffering from a cognitive or mental health impairment at the time, if that was a cause of the failure to get consent.
They would still have to believe the other person was consenting.
Attorney-General Mark Speakman on Thursday evening said the definitions were developed with forensic mental health experts and consistent with other criminal laws.
"This is not a 'get out of jail free' card - an offender with a cognitive impairment or mental health impairment can still be convicted if all elements of the case are established beyond reasonable doubt," Mr Speakman said.
Labor, the Greens and One Nation are pushing for changes to the exception, which was debated in the upper house on Friday.
A Greens amendment would tweak the bill to provide that the impairment must be "the" cause - rather than "a" cause - of the failure to seek consent. Labor wants it be a "substantial cause".
If One Nation gets its way, a person would have to show they have a "substantial" cognitive impairment before they could fall within the exception.
Frontline organisation Rape & Domestic Violence Services Australia criticised the bill's exception, warning it is too broad.
The section will be used "as a loophole for accused persons to avoid the requirement to take steps to establish consent" if the bill is passed, CEO Hayley Foster wrote to MPs this week.
Other organisations including Domestic Violence NSW, ACON and the Older Women's Network also signed the letter.
Ms Foster told AAP she was surprised to see the bill didn't require an accused to prove they had a "substantial cognitive impairment" to fall within the exception.
There are already protections in the criminal justice system for people with mental health problems, she said.
"There shouldn't be additional protections for people who are accused of sexual assault than (there are) for other crimes," Ms Foster said.
Earlier in Friday's debate Liberal MLC Natalie Ward disputed a number of claims about the bill made by One Nation MP Mark Latham, who said "millions of long-term, loving couples" would be trapped by a bill that did not allow for "natural" or "spontaneous" sexual activity.
"The government's bill does not make consensual sex illegal," Ms Ward said.
"Consent must be present throughout every sexual encounter no matter the relationship between the adults participating. This is true of the current law and the bill does not change this."
Mr Latham then moved an amendment on Friday that he said would seek to "provide clarity" on what the bill "actually means".
Passage of the bill is all but assured, no matter how the debate on the amendments is resolved.
Years in the making, the historic reform has support from the government, Labor, the Greens and other minor parties.
It comes after Victoria's government last week announced it would introduce similar changes to that state's Crimes Act.
Australian Associated Press