Two years ago, a news investigation found abuse and violence perpretrated by staff against women at the Yarl’s Wood detention centre. And an independent report found Yarl’s Wood was holding vulnerable women for long periods in conditions causing serious distress and worsening mental health problems.

This week a campaign led by Women for Refugee Women has exposed how severely traumatised survivors of rape and sexual violence are still regularly being locked up at Yarl’s Wood detention centre – breaching the government’s own policy on not detaining victims of violence. One woman reported today that she was offered no help or support even when she threatened to take her own life.

Every year more than 1,500 women are forced into detention centres. We’ve been told before that they are often worse than prison – at least in prison you know when your sentence is served. And yet these are not places for people who have committed a crime; only people who have attempted to claim asylum or whose papers have expired often through no fault of their own.

This is the latest in a catalogue of horrific failures in Britain’s detention centres, where abuse and malpractice now seems endemic.

The isolated Victorian detention centre in Dorset, The Verne, is finally shutting its doors as the Shaw Review into abuse in the immigration removal system rolls on. This is a small step in the right direction. But Brook House, where undercover journalists filmed asylum seekers being choked and mocked over self-harm in September, still remains active as do other such centres.

The cruelty of our detention system serves no purpose – just 15% of asylum-seeking women leaving detention were eventually removed from the UK. Incarcerating people for exercising their right to claim asylum is wrongheaded economically as well as ethically, and research shows systems that do not use detention do not have additional problems maintaining contact with asylum seekers.

So why does the system persist?

Government has set net migration targets it cannot meet. Maintaining the fiction that migration is responsible for all our social and economic problems requires being visibly seen to do something to get numbers down. Detention centres, and all aspects of the UK’s “hostile environment” strategy for migrants from passport checks at hospitals to raids on workplaces, are about the appearance of tough action.

In the meantime, lives continue to be put at needless risk, and a country that prides itself on its values continues to lock up torture victims.

It should be a matter of basic practice that asylum seekers are screened for traumatic experiences before they go through the system. But tweaking this regime will not solve it – it’s time for the detention centres to go altogether. They haven’t been fixed in spite of years of promises, and they aren’t working.

Phasing out detention centres would provide a light at the end of the tunnel for all those enduring them. And it would send a powerful signal about the kind of society we want to be.