The Home Office has failed to protect vulnerable migrants it locks up in detention centres, a high court judge has ruled.

Mrs Justice Jefford found an unlawful failure of the “systems” designed to protect immigration detainees from inhuman and degrading treatment under article 3 of the European convention on human rights and that these failings had been going on for years. The judgment could affect thousands of people who are at risk behind bars.

The case was brought by two detainees from Egypt and Bangladesh who were detained between 28 July 2023 and 11 March 2024.

Both were detained at Brook House immigration detention centre near Gatwick, where undercover filming by BBC Panorama revealed abuses of vulnerable detainees by guards in 2017. The subsequent Brook House public inquiry raised multiple concerns about risks for vulnerable immigration detainees.

The focus of the case was on a safeguard known as rule 35. It requires medical practitioners at detention centres to issue reports to the Home Office when they have concerns about specific vulnerabilities, such as suicide risk or mental health problems, which may make a person unsuitable for immigration detention so, the Home Office can urgently review their continued detention.

The men who brought the case displayed worsening mental illness and signs of serious self-harm while in detention. Both had periods on constant suicide watch, after a separate process known as the assessment care in detention and teamwork process (ACDT).

But despite being on suicide watch, neither had their suitability for continued detention assessed.

The judge found significant evidence the system had not been working for years, and that many of these issues were known about at least as far back as 2017.

She raised concerns about the “disconnect” between those being managed under the ACDT process and the low numbers of rule 35 reports issued, particularly those relating to mental health problems or risk of suicide.

The judge found the home secretary provided no convincing answer or evidence to justify why there were so few of these reports, particularly for suicide risk, set against the number of people each year under constant supervision.

She said: “Since at least the period covered by the Brook House inquiry there is a clear and persistent picture of a failure of the system intended to protect the article 3 rights of adults at risk.”

Lewis Kett, of Duncan Lewis solicitors, the firm representing the two men who brought the high court challenge, said: “Our clients welcome this important judgment that not only was their own detention and treatment at Brook House unlawful, but that their experiences are emblematic of a sustained failure by the home secretary over a number of years to properly run systems that safeguard vulnerable people in detention from serious harm.

“This has put countless immigration detainees with serious mental illness or suicidality at a real risk of harm.”

Detention charities are calling for rules that exist on paper to protect vulnerable detainees to be implemented.

Emma Ginn, the director of Medical Justice, said her organisation continued to see a comprehensive failure to complete these reports for those who require them.

“In the last few months Medical Justice asylum seeker clients who arrived in the UK on small boats and who were detained to be sent back to France for the UK-France scheme who would have met the threshold for these reports did not have them. This included an individual who had attempted suicide in detention.

“It is entirely possible that a failure to prepare one of these reports could be a factor in whether an individual attempts suicide or indeed dies by suicide.”

A Home Office spokesperson said: “We are committed to ensuring that detention and removal are carried out with dignity and respect and have made progress in improving detention safeguards.

“These include regular reviews once a person is detained to ensure their detention remains lawful, appropriate and proportionate.

“Out of the 30 recommendations from the Brook House inquiry in September 2023, 25 have been met and closed, and we continue to embed these improvements.”