On the 20 March the government asked pubs, restaurants, gyms and other social venues to close. Detention centres, however, are still running. Inside, people are unable to follow the government’s instructions to socially distance. Hygiene and ventilation is poor and cleaning products are scarce. I have heard deeply concerning first-hand accounts of this rapidly developing crisis.

"If there's an outbreak in here we’ll be like sitting ducks” Steven, one of our clients at Bail for Immigration Detainees, told us. “80% or 90% of us will pick it up because we are all here together. If someone sneezes we’ll get it. The air is recycled, there's no windows or fresh air”. Steven (not his real name) has built his life in the UK and is separated from his four British children as a result of immigration detention.

The situation is critical for those that have health conditions that place them into a high risk category as defined by Public Health England. One of our clients is asthmatic and, since the COVID-19 outbreak, has been waking up with panic attacks and shortness of breath, and a feeling that he is suffocating. Another has hypertension and severe mobility issues and had been recognised, even before the outbreak of COVID-19, as being unfit to be in detention by doctors and medical experts examining his records.

Our clients have never felt that they are treated with basic dignity. This has only become more apparent in the last few weeks. Neither the government nor the private companies contracted to run detention centres have bothered to communicate the implications of COVID-19 to the detainees it places at risk. “We don’t find out nothing from them (staff), we have to ask each other.” said our client David (not his real name) detained in Brook House. “Today we can move around but just within the wing. We don’t have rights. Britain isn’t civilised, look what it is doing to people. I would never have thought this would happen in Britain... They don’t value people here.”

The Home Office holds around 400 people under immigration powers in prisons scattered across the UK. Like time-serving prisoners, they are subject to severe restrictions on liberty and isolated from legal and other forms of support without access to the internet, mobile phones or faxes. This has only worsened over the last month – clients have reported being locked in their cells for 23.5 hours per day.

88 prisoners and 15 staff have already tested positive for COVID-19, and three prisoners have died. The government announced on Saturday that 4,000 prisoners would be temporarily released to limit the spread of infection. The significance of this from a government which wasted no time announcing tougher sentencing measures cannot be understated. It is therefore all the more inexplicable that people who have completed their criminal sentences remain detained under immigration powers.

This is not only reckless, but pointless and potentially unlawful. Immigration detention exists for the convenience of the Home Secretary, to facilitate enforced removal from the UK. Where an individual cannot be removed there is no lawful basis for detention. In the overwhelming majority of cases removal is simply not possible (and certainly not justifiable as an essential activity in the current context) due to the global chaos caused by COVID-19.

Since 20 March, we have represented 18 clients in bail hearings. We made representations on the basis of COVID-19, and bail was granted in all 18 cases. Clearly judges do not believe people should be in detention at this time. It was particularly concerning that in one of these cases the Home Office argued that “the applicant has cited COVID-19 in grounds for bail… these risks exist outside of a prison environment as much as inside one”. Whether this represents the view of a single caseworker or an institutionalised approach to decision-making, it is at odds with common sense and Public Health England guidance, and puts lives at risk.

Detention is only possible because the Home Office has very wide and discretionary powers of detention unfettered by the constraints that exist in the criminal justice system. The use of immigration detention is in many respects de facto outside and above the law. People are held indefinitely and the decision to detain is made by a civil servant without judicial oversight.

Only four months ago the Supreme Court found that the Home Office’s detention policy does not provide clear and objective criteria as to how to assess the risk of absconding in decisions to detain. The court also found the policy to lack the certainty and predictability necessary to be considered a law. Although the case referred to a specific cohort of immigration detainees – asylum seekers detained pending transfer to another EU state – it calls into question the very legality of the entirety of the UK’s immigration detention policy.

Unlawfulness is at the heart of the UK’s detention system. In the last year alone the Home Office was forced to pay £8.2 million to 312 people who were found to have been detained unlawfully. Many cases are settled out of court, with the applicants made to sign non-disclosure agreements. Staggering though these figures are, they may well be just the tip of the iceberg in a detention system where access to quality legal advice is scarce and many other cases are not pursued due to lack of legal representation.

The government is seeking to further erode the few existing safeguards in a system weighted against migrants at every stage. Consistent with the spirit of successive governments the Conservative manifesto promised to "update" the Human Rights Act and ensure judicial review "is not abused to conduct politics by another means or to create needless delays". Challenging (frequently poor) Home Office decisions and unlawful policies – already fraught with difficulty – may become impossible.

The vast sum of taxpayers’ money and the human cost underpinning it seem to be viewed by the Home Office as collateral damage. Through the cold lens of economic calculation and political expediency it is a price worth paying in return for maintaining a system where incarceration can be practised with so few safeguards.

In a country that claims to prize the value of liberty we have built a brutal system under which people can be locked up without trial or time limit. That system rests on a logic that certain human lives as less worthy of dignity, rights and protection.

The deficiencies in this logic have surely never been clearer. It has always been true that the practice of immigration detention corrodes the moral and social fabric of society. Equally the harm caused by immigration detention has never been neatly confined to a specifically identified group of disposable non-citizens – it ripples out into families, into communities and society at large. It now also poses a very urgent risk to public health because to leave one group unprotected, at the mercy of a deadly virus, is to threaten us all.

This article is part of the Unlawful State series where we investigate unlawful decision making by the UK government. We also hear from pioneering NGOs using the law to tackle the problem. See here for more.