The decision to reject an appeal to increase the sentence of a man who killed a woman during sex has been branded “the ultimate victim-blaming”.

Sam Pybus, 32, was jailed for four years and eight months in September this year after pleading guilty to the manslaughter of Sophie Moss, after he applied pressure to her neck when they had sex at her home in Darlington in the early hours of February 7.

It was accepted by the sentencing judge that married Pybus did not intend to kill the mother-of-two and his remorse was genuine.

On Friday, an appeal to increase his sentence was rejected at the Court of Appeal.

Labour MP Harriet Harman said the ruling was “not justice and it’s not justice for Sophie and it’s not Pybus being held accountable”.

She added: “And this confirms why we must have a new law to make sure that men who claim rough-sex-gone-wrong defence are prosecuted for sex murder with a mandatory life sentence.

“This is the ultimate victim blaming and it’s the ultimate male excuse for domestic violence.”

The Centre for Women’s Justice said the case suggested Sophie was “partly culpable for her own death”.

Ms Harman has been a lead campaigner in abolishing the rough-sex defence and Pybus’ case was referred to the Court of Appeal after she wrote to the attorney general to complain about his “unduly lenient” sentence.

In 2019, she told the Commons men “are literally getting away with murder by using the rough-sex defence”.

On Friday, the Court of Appeal heard from Attorney General Suella Braverman QC, who said Sophie could not consent to any act after she became unconscious, and that the risk should have been “obvious to Pybus”.

She said: “Sophie Moss could not, and did not, consent to being strangled beyond the point of consciousness.

“In order for Sophie Moss to have died at the hands of the offender, it was necessary for him to strangle her to the point of unconsciousness and beyond.

“She would no longer have been an active participant in the act the offender claims she was enjoying.”

Sam Green QC, for Pybus, said there was no evidence about how long he had strangled Ms Moss for and added “We don’t know when unconsciousness occurred.”

Lady Justice Macur, sitting with Lady Justice Carr and Mr Justice Murray, declined the Attorney General’s request to refer the sentence.

“We find on the basis of the facts in this case, on the evidence and not speculation… that there was no error of law which can be identified in terms of the assessment of the judge as being irrational or perverse,” Lady Justice Macur said.

“We do not accept the submission of Madam Attorney General that the judge fell into error by considering the starting point in this case to be identified… as one of six years,” she continued.

Lady Justice Macur agreed with the sentencing judge that “the nature of the evidence was such that it would not be possible to expect a jury to convict this offender of murder” and there was no evidence capable of proving that Pybus intended to kill or cause really serious harm to Ms Moss.

The judge also added that the evidence suggested Ms Moss had consented to the practice of erotic asphyxiation.

“The evidence before the court, and that is independent of the offender, suggests that her participation in that practice was consensual and also initiated by her,” Lady Justice Macur said, adding that her consent was not enough to be a defence to manslaughter.

Lady Justice Macur said Ms Moss’s death “has left a great loss to those who loved her”.

The judge concluded: “Bearing all the circumstances of this case in mind, we are not persuaded that the judge was wrong in categorisation, was wrong in the uplift he applied… or was wrong in the element of discount that he gave for mitigation and then for his plea of guilty.”

The Centre for Women’s Justice said Pybus’ case “demonstrates a complete lack of understanding of the nature of violent male offending”.

Director Harriet Wilstrich said: “Unfortunately the attorney general was bound to accept the case as presented by the prosecutor in the lower court, and in particular that Sophie Moss ‘enjoyed asphyxiation’.

“This is a form of victim-blaming, suggesting that she was partly responsible for her own death.”

The ruling has also been criticised by Pybus’ ex-wife, Louise Hewitt, who said it proves the “rough-sex defence is valid and works, even though the Domestic Abuse Act was supposed to abolish it”.

The Domestic Abuse Act was brought into law in April this year.

Section 72 of the Act says that a person cannot consent to the infliction of serious harm, or by extension, their own death, for the purposes of obtaining sexual gratification.

It means that where a defendant claims the victim’s death, or the injuries they sustained, were the result of “rough sex gone wrong”, they will remain liable to prosecution for a relevant offence.

Ms Hewitt said Pybus’ sentencing “doesn’t reflect the lifetime of grief that has been inflicted on Sophie’s family, especially her two sons who have to grow up with that narrative about their mum”.

She said: “I think it was a very lenient sentence and it places the responsibility on Sophie, which to me is victim-blaming and that should not be allowed to happen.”