The current system also appears to be costing UK taxpayers dearly: the Home Office spent £108m on detention from 2017-18, according to a joint study by Cambridge Econometrics and Liberty. Their report, published in May, suggested that a 28-day time limit on detention could save the as much as £35m.

These reports follow a July 2018 review published by UK former prisons and probation ombudsman Stephen Shaw, which criticised the ‘deeply troubling’ length of time that people were being detained in immigration removal centres (IRCs).

This was Shaw’s second review of the UK’s immigration system. He commended the decline in the average length of detention from 91 days in March 2015 to 83 days in February 2018. However, he noted that the number of people held for more than six months prior to release or deportation had actually increased from 275 in January 2016 to 305 in December 2017.

These revelations emerge as momentum for legislative change in this area is gathering pace. The Immigration (Time Limit on Detention) Bill 2017-19 was presented in Parliament on 5 December 2018 and is awaiting its second reading in the House of Commons. It proposes to add a provision to the Immigration Act 1971 to ensure individuals cannot be detained for more than 28 days in any of the UK’s three legal jurisdictions.

Stephanie Harrison QC, a barrister at Garden Court Chambers, has been working on the proposed amendment. She says the reports by Shaw and others demonstrate the need for a strict statutory time limit. ‘The overriding recommendation from the initial Shaw review was to reduce the numbers in detention and to avoid detention in particular of those with serious mental health problems,’ she says. ‘That just hasn’t happened. That illustrates the institutional culture within the Home Office is incapable of reform and that does mean that Parliament has to step in to regulate this power.’

In a statement, a Home Office spokesperson told Global Insight: ‘We are looking at the issue of time limits in the context of a detention system that’s fair to those who may be detained, upholds our immigration policies, and acts as a deterrent to those who might seek to frustrate those policies.’

Most other European countries follow the Returns Directive, which states that immigration detention cannot normally exceed six months. ‘There needs to be a very clear time limit to focus the minds of civil servants and the Home Office so that people don’t just end up languishing simply because no decision is being made,’ says Nicolas Rollason, Secretary of the IBA Immigration and Nationality Law Committee.

The bill has strong cross-party support. Harrison says exposure of abuse of detainees by staff at IRCs, such as Brook House in 2017, has highlighted the need for Parliament to act. ‘There’s no doubt the Brook House scandal exposed systemic failings across the board in the treatment of mentally ill people and is a window into what the culture is like in those places,’ she says. ‘There couldn’t be more compelling evidence of just how abusive immigration detention facilities are.’ The Home Office has asked the Prisons and Probation Ombudsman to undertake an investigation into the alleged mistreatment of detainees at Brook House.

Kaweh Beheshtizadeh, an immigration solicitor at Fadiga & Co in London, believes the absence of a time limit has caused irrevocable harm. ‘It is in itself brutal, inhuman even, to keep people in detention while they don’t know when they are going to be released or when they are going to be removed,’ he says. ‘There must be a limit, especially for people with no criminal convictions.’

Beheshtizadeh has first-hand experience of the UK’s immigration system, having arrived in the country in 2004 in the back of a lorry from Iran. He learnt English almost from scratch, was granted asylum in 2006 and went on to qualify as a solicitor. Today, Beheshtizadeh represents numerous clients that have been held in immigration detention, often for lengthy periods. One client, who came to the UK in 1999 to claim asylum, was detained on four separate occasions from 2009-2016, totalling 1,231 days.

Beheshtizadeh could not challenge his client’s first period of detention because the six-year limitation period for false imprisonment had already passed, but challenged the remaining 850 days on the grounds they were unlawful. The Home Office settled the case in December 2018, a month before the substantive hearing was scheduled.

Beheshtizadeh is still trying to secure his client leave to remain as a stateless person. He says this case illustrates how the UK’s ‘inhuman and degrading’ immigration system is costing the taxpayer unnecessarily: ‘If the Home Office settled at the very early stage of the claim, a significant amount of public money could have been saved.’

A Home Office spokesperson said: ‘Any decision to detain someone is reviewed by a Detention Gatekeeper who acts independently from referring and case working teams to ensure an individual’s suitability for detention has been fully assessed, and any vulnerabilities have been considered.’ Between 2012 and 2017, the Home Office paid out £21m in damages for unlawful detention claims.