The so-called "rough sex gone wrong" defence will be outlawed in new domestic abuse legislation, a justice minister has told MPs.
Alex Chalk said it was "unconscionable" that the defence can be used in court to justify or excuse the death of a woman "simply because she consented".
He said it would be made "crystal clear" in the Domestic Abuse Bill that it was not acceptable.
The bill, for England and Wales, is due to become law later this year.
Jess Phillips, Labour's shadow minister for domestic violence and safeguarding, spoke on an amendment proposed by Labour MP Harriet Harman and Conservative MP Mark Garnier to the legislation, to prevent lawyers from using the defence, but withdrew it following assurances from Mr Chalk.
The campaign group We Can't Consent To This, which wants the defence outlawed, said the minister's response was "a big step forward".
The group says the "rough sex" defence can result in a lesser sentence.
Campaigners want to make it the expectation that murder charges are brought against those suspected of killing a person during sex.
As it stands, if someone kills another person during sexual activity they could be charged with manslaughter alone. To murder someone, there needs to have been an intention to kill that person or to cause them grievous bodily harm (GBH).
We Can't Consent To This has collated 60 examples of women "who were killed during so-called 'sex games gone wrong'" in the UK, since 1972.
The group claims that 45% of these cases ended in a "lesser charge of manslaughter, a lighter sentence or the death not being investigated as a crime at all".
There are also 115 people - all but one of whom were women - who have had to attend court where it is claimed they consented to violent injury, the group has said.
The violence used in the non-fatal assaults included waterboarding, wounding, strangulation, beating and asphyxiation.
Speaking to MPs at the Commons' Public Bill Committee, Jess Phillips said: "The law should be clear to all - you cannot consent to serious injury or death, but the case law is not up to the task."
She said when a woman is dead "she can't speak for herself" but any man charged with killing a woman or a current or former partner could "simply say she wanted it".
"This is why we must change the law," she said.
Alex Chalk, replying for the government, said: "It is unconscionable for defendants to suggest that the death of a woman is justified, excusable or legally defensible because that woman had engaged in violent and harmful sexual activity which resulted in her death, simply because she consented."
He said that would be made "crystal clear" in the Domestic Abuse Bill but he was concerned the wording of the amendment would allow defence lawyers "wiggle room".
He said the government's approach would be set out by the report stage - the next stage in the bill's progression through Parliament. Ms Phillips said she was satisfied with this assurance.
The We Can't Consent to This campaign group said what had happened in Parliament "was genuinely a big step forward", adding: "We should know within weeks what their proposals are and if they've gone far enough."
Earlier this month at Prime Minister's Questions, Conservative MP Laura Farris said the government had taken a lead on tackling domestic abuse, but said there was "an ugly dimension that remains unresolved" on the issue of the rough sex defence.
In response, Prime Minister Boris Johnson said: "We are committed to ensuring that the law is made clear and that defence is inexcusable."