Claire Waxman is drinking tea from a white mug bearing the slogan: “I’m not bossy, I just have better ideas.” It was a present from her daughter, she explains, rather than her colleagues, but for the record, London’s first commissioner for victims certainly is brimming with ideas.

Having published the London Rape Review last summer, a study of more than 500 rape cases exploring why prosecution rates are so low, Waxman is about to launch a crucial piece of research on one controversial aspect of the process: the requirement for rape complainants to hand over their mobile phones for police examination. Reading text messages that may shed light on any relationship with the accused is one thing, says Waxman, but she is concerned that the practice is leading to far broader digital fishing expeditions that drag out investigations and lead to victims dropping out. Victims, she believes, are being treated more like suspects.

“It’s adding on six months, if not longer, on investigations,” says Waxman, whose initial review found it now takes almost a year from reporting an attack to a file being submitted to the Crown Prosecution Service (CPS). “The longer it takes, [the greater] the impact on the victim and the likelihood of them withdrawing from the process, because in that time frame they can’t really access counselling services freely – they’re told that if they do so, their notes may be requested by the police and the CPS.”

The entire process, she says, is far too “invasive ... The whole way in which we structure these investigations is very much against the rape victim and against their ability to cope and recover.” Some 58% of alleged victims in her review had dropped out before their case reached court – many citing the distress caused by reliving the details during the investigation or a desire to move on from a traumatic experience. (Interestingly, the attrition rate was three times higher for female rape victims than male ones).

The issue of so-called digital disclosure shot to public attention in 2017, after a handful of high-profile rape trials collapsed following phone messages or pictures coming to light. After that, says Waxman, police started routinely asking for mobiles to be handed over, and she has heard some hair-raising stories about the way private information has been used. She was particularly struck by one case in a which a woman had a recording app on her phone, which she used for work meetings. “She didn’t realise the app often stayed on and continued recording, and so it recorded conversations between her and her partner. Those conversations were then listened to by the police.” The woman was asked by the police “in quite an attacking way” why she had discussed the case at home with her partner. “It was quite shocking because they were looking at material that really shouldn’t be looked at, because it’s like surveillance. It’s almost like going into a coffee shop where you’re sitting with your partner or friend discussing, as you would, what’s happening in your life, personal things, and a police officer recording that.” The case was subsequently dropped.

Another rape survivor was horrified to find a selfie in which she was smiling, taken hours before she was attacked, being used out of context in court. “They used it to say: ‘Look, she looks very happy’, but they didn’t talk about the time it was taken. And she had no right to respond.”

Waxman’s review will look at what intimate information police are asking for, what impact wading through vast caches of phone data has on the length of investigations, and how much of it is ultimately useful in court. “I speak to the judiciary about it and they say: ‘I’m not interested in what she said to her friend about sex.’ But the police and CPS position has been very much about: ‘Get everything and then we’ll see what’s reasonable, what we need to consider, because there could be something in that that undermines the case.’” Even in cases of stranger rape where there is no relationship with the accused to examine, she says, school or medical records are routinely scrutinised for anything potentially affecting the victim’s credibility.

The Metropolitan police is currently trialling a data-search tool called Magnet, to see if it can sift out relevant information from victims’ phones without undue invasion of privacy. But Waxman’s hunch is that some legal constraints on what can appropriately be accessed may be necessary. “If you think about the younger generation and how they use their phones – they don’t speak on a phone, everything is recorded and sent as a voice message. So everything is on there, every thought, every feeling.”

It’s clear that, after two and a half years at City Hall, Waxman still approaches the job from the perspective of someone who has herself been a victim of crime. She was stalked for more than a decade by a former fellow student at her sixth-form college, who repeatedly defied court orders to stay away; the experience prompted her to found the charity Voice4Victims, campaigning for improved legislation for victims of crime generally. She recently revealed that, 14 years on, she was still waiting for a court-ordered compensation payment.

She is clearly uncomfortable discussing her experience now – she deliberately doesn’t use her stalker’s name in interviews – and thought hard about the risks of taking a job that might bring her to public attention. But she says the experience taught her how vulnerable victims can feel. “You have this misconception that when you report to the police, everything will then be OK. I think the very sobering and sad realisation is that not only is it often not OK, it makes it far worse for that individual because of how fragmented the justice system is, how a victim is very much the afterthought throughout the entire process.

“You’ve already been disempowered by whatever happened and that justice process only works to disempower you further.” She lost count of the number of times she had to take her stalker to court but “each time I vowed never to go back into it again because it was so awful. But I didn’t see any other way out. It was all-consuming, highly traumatic, re-victimising.”

Waxman is delighted that the Met has established a stalker threat assessment centre, a pilot project seeking to identify at an early stage obsessively fixated stalkers who may not be deterred by the law. Police attitudes have improved, she says. However, “I still get regular cases coming to me and I’m looking at it thinking: ‘I can’t believe the police haven’t gripped this.’ It concerns me that we’re still not recognising a lot of these behaviours.”

Elsewhere in her work, she welcomes potential moves to curb the so-called “rough sex” defence used in several recent murder trials, by men claiming to have strangled or beaten women to death in sex games gone wrong. (The former Labour minister Harriet Harman has led moves to tighten the law, as part of a domestic abuse bill going through parliament this spring.) “It’s being used far more widely now as a defence and it’s incredibly concerning, because these victims are not consenting to be killed.”

Waxman is concerned about whether there will be enough money to make good on the bill’s central premise, a duty on local authorities to provide enough refuge places for women fleeing domestic violence. “With all these things, unless there is proper investment and sustainable funding, the issue on the ground is that victims and survivors really struggle to access quality and specialist support services.” Years of cutbacks to the police, CPS and courts have had a “huge impact” on the service that victims of crime receive. “The whole system has been stripped away over the last decade. I don’t say this lightly: the justice system has been creaking for years and it’s at breaking point; it needs proper investment.”

Which brings us to the role of Priti Patel, the home secretary. Patel has campaigned for stronger victims’ rights since she was a backbencher and Waxman, who has had several meetings with her over the years, stresses that she has never found Patel anything other than “very supportive” and “very lovely to me”. But does she think the home secretary makes a credible champion of victims with bullying allegations hanging over her? “Not currently now, unfortunately. Whether there’s truth in the allegations or not I don’t know, but obviously that does impact her currently. If you are committed to supporting victims, you don’t really want to be accused of creating victims or making someone a victim of abuse.”

Her current post is in the mayor of London’s gift, and with Sadiq Khan up for re-election in May, Waxman cannot be entirely sure what the future holds for her. But she clearly intends to make the most of whatever time she has. “It’s a role that should be here regardless of who the mayor is; without it one doesn’t know what’s happening on the ground for victims and survivors. It’s influenced so much change not just here in London but the national agenda,” she says. “I’m not political, for me it’s all cross-party work. I just want the work done for victims.” And with that, she heads back to her desk, clutching the cold tea she hasn’t had time to drink.

• This article was amended on 12 March 2020. Earlier versions said the attrition rate was three times higher for male rape victims than female ones, when it is three times higher for female than male.