Police Scotland has been accused of acting in a “sexist and statistically incoherent” way when it comes to recording the sex of sexual predators.

The criticism of the force came in a submission to Holyrood’s Petitions Committee, as part of their inquiry into how the sex of people charged or convicted of rape or attempted rape is recorded.

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Giving evidence to the MSPs, the force said officers “do not routinely ask the sex or gender of people they interact with” and that require “no evidence or certification as proof of biological sex or gender identity.”

There are however, “circumstances where the issue of biological sex may require to be explored for a legitimate policing purpose”, including sexual offences involving “penetration of the vagina, anus or mouth of the victim by a penis or surgically constructed penis.”

“In order to charge a person with rape, it is evidentially critical to ascertain if they have a penis or surgically constructed penis. Hence, self-identified gender is of no relevance to the charge and is not evidentially influential in proving the crime.”

The force said that there were four ways in which a woman would be recorded as having committed rape.

Firstly if they were art and part of the crime, that is they aided the man responsible for the penetration. This covers all of the women accused of rape between 2016 and 2020.

Secondly. if they had a full gender recognition certificate and “then commits rape (providing they have a penis).”

Thirdly, if the attending officer is “satisfied the individual presents as a female and subsequently records them as such on our crime systems.”

And fourthly, where a person “born female transitions to male (who has a surgically constructed penis) commits rape but does not have a full gender recognition certificate and so remains legally female.”

The academic and research collective Murray Blackburn Mackenzie, who started the petition back in July 2021, triggering the committees’s probe, is to give evidence at tomorrow morning’s session.

Ahead of the meeting, they told MSPs the police policy approach was flawed, particularly the lack of indication over exactly what they meant by “presents as female”.

“Typically the term simply refers to gender stereotypes,” they said. “This means for those coming into contact with the police for the first time, data recording in relation to sex is left dependent on the extent to which any individual officer believes a person conforms to ‘feminine’ ideals.

“We think that this is sexist and statistically incoherent.”

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They said the recent cases involving Isla Bryson/Adam Graham and Andrew Miller showed that the force was “an organisation that treats the wishes of violent male offenders as paramount.”

Bryson, a double rapist who changed gender while waiting to stand trial, was arrested and recorded as male but was allowed to be processed in court as a woman.

Miller, who identifies as a transgender woman and is said to be in the process of transitioning, abducted a primary school pupil while dressed as a woman before sexually assaulting the girl repeatedly over more than 24 hours.

He was recorded from arrest onwards as male at his own request.

MBM said the Police Scotland policy meant it was Miller’s decision, “not their own stereotype-based policies, that led to his being recorded as a male charged and convicted of sexual assault.”

They said if Bryson had claimed a trans identity ahead of being charged his offences, these would have been recorded as committed by a woman.

“It should be obvious that this is a misguided approach to data collection.”

A police spokesperson said: "The sex/gender identification of individuals who come into contact with the police will be based on how they present or how they self-declare, which is consistent with the values of the organisation.

"Police Scotland requires no evidence or certification as proof of biological sex or gender identity other than a person's self-declaration, unless it is pertinent to any investigation with which they are linked as a victim, witness or accused and it is evidentially critical that we legally require this proof, or there is reason for further enquiry based on risk. We would look for the most sensitive way to acquire this information."