In addition to challenging the role of the European Court of Human Rights in immigration issues, the current Secretary of State for the Home Department (“SSHD”) has proposed limits to the domestic judiciary’s role as regards immigration decisions.  Despite this, the judiciary’s role overseeing the SSHD’s decisions in regard to detention of migrants remains significant. A recent case suggests that when the SSHD makes detention decisions, in certain cases she is under a more onerous duty of inquiry than previously thought. This highlights the extent to which the court’s oversight on detention decisions remains significant, even as its powers on immigration generally are being challenged. The case, R (AH and IS) v SSHD [2025] EWHC 3269 (Admin) (“AH”), clarifies the scope of the SSHD’s Tameside duty of inquiry when making the decision to detain individuals under immigration powers where there is prima facie evidence they have severe mental health issues.

This case is one in a series addressing long-standing issues at Brook House Immigration Removal Centre (“IRC”). Like the recent judgment in Medical Justice v SSHD [2025] EWCA Civ 251, it deals with medical assessments of individuals held under immigration powers.

Background

This was a judicial review of the SSHD’s decision to detain two claimants (“IS” and “AH”) at Brook House IRC between July 2023 and March 2024 [1]. Both claimants were released from an initial period of detention due to serious mental health issues. The proceedings scrutinised the SSHD’s approach in detaining the two claimants subsequent to their release. During the second period of detention for each claimant, IRC staff had recorded that each had experienced suicidal ideation and self-harm. This was prima facie evidence of the claimants’ deeper mental health issues. Despite this, neither was subject to a Rule 35 report (Rules 35(1) and 35(2) of the Detention Centre Rules 2001), which would have led to their detention being reconsidered by the SSHD. 

The challenge advanced different grounds of appeal for each claimant. AH’s grounds included allegations that detention was vitiated on the basis that the SSHD had failed to comply with her own policies, including those related to the use of Rule 35 reports and the Adults At Risk (“AAR”) Policy [3]. IS’ grounds included allegations that the SSHD had failed to adequately consider the claimant’s previous mental health (per the relevant AAR reports).

Rule 35 and the AAR Policy

The Detention Centre Rules 2001 (the “Rules”) outline, regulate and manage IRCs including the handling of vulnerable persons who are detained there. They include a requirement that every person brought into detention is given a physical and mental exam by a medical practitioner within 24 hours of admission (Rule 34(1)). Rule 35 creates an obligation for the medical practitioner to report to the SSHD of any person “whose health is likely to be injuriously affected” by detention (Rule 35(1)), “any detained persons he suspects of having suicidal intentions” (Rule 35(2)) and “any detained person who is a victim of torture” (Rule 35(3)). Reports that AH and IS had self-harmed and had experienced suicidal ideation should have triggered fresh Rule 35 reports, but did not. Mrs Justice Jefford in the High Court held in AH that “the Rule 35 process did not work properly” [99]. 

Rule 35 Reports are critical to the operation of the AAR Policy, which uses the reports to determine the threat posed by detention to a given detainee. The AAR Policy establishes that there is a presumption against detention which is strengthened where someone is particularly vulnerable (e.g., when they have medical concerns, have experienced a traumatic event including torture, or for other reasons). For Levels 1 and 2, vulnerability can be outweighed by “compliance” issues, including that the individual may abscond. Individuals assessed as Level 3, the most severe level, should only be considered for detention if there are considerations relating to the imminence of removal or public protection (AAR Policy, p. 24). Under the AAR Policy, it is “very unlikely” that issues related to the individual’s compliance alone would warrant detention for those assessed as Level 3 (AAR Policy, p. 24). For detention to remain lawful, immigration control considerations must outweigh the presumption in favour of release/against detention.

Under the AAR Policy, Individuals are assessed at a certain level of risk in accordance with their circumstances and “on the basis of the available evidence” (AAR Policy, p. 25). Significantly, the policy states that in conducting the AAR assessment, decision makers “should use the most up to date information each time a decision is made” because “the available evidence of a condition or traumatic event, can change over time” (AAR Policy, p. 6). Furthermore, it confirms that “there should be an ongoing assessment of risk made by the caseworker throughout the period of detention which will facilitate the identification of any emerging risk or changes to risk factors” (AAR Policy, p. 25). 

For both AH and IS, the SSHD failed to reconsider the decision to detain after the claimants displayed symptoms of severe mental illnesses in their second period of detention. This was due to a lack of relevant Rule 35 reports and failure to access and consider each individual’s mental health history (including issues leading to IS’s successful judicial review of his previous detention). 

AH’s History and Detention Decision

In his initial detention, AH self-harmed multiple times. He reported that he had witnessed domestic violence and physical abuse as a child [36]. He was moved to Brook House in 2018, where a Rule 35 report found that he may have been a victim of torture, making him Level 2 under the AAR policy. 

In his second period in detention, AH informed staff that he had recently self-harmed/attempted suicide but had no current suicidal thoughts [48]. He informed staff he had previously received mental health intervention while in custody, but records of this were not identified by staff [48]. A Rule 35 report was triggered, which confirmed that he may have been a victim of torture but failed to identify his previous mental health issues. The SSHD found that he was a Level 2 under the AAR Policy and found the presumption against detention was outweighed by his high risk of absconding [51]. Despite further self-harm in 2024, no further Rule 35 report was triggered. He was released due to solicitor intervention in March 2024. The SSHD argued that in AH’s case, “isolated and/or minor incidents from years earlier had no or no significant bearing on the most up to date information as to [his] mental health,” [52] in part because he was “properly managed” during his initial detention [54]. 

IS’s History and Detention Decision

IS’s initial period was from 2016 to 2018 [97]. He was detained at Brook House IRC for 11 months of his 16 month detention period, following which IS successfully challenged the SSHD’s decision to detain him via judicial review on the basis of his high vulnerability and the lengthy period of constant supervision (75 days) ([98], IS (Bangladesh) v SSHD [2019] EWHC 2700 (Admin), in which the court found breaches of Articles 5 and 8 ECHR). 

During his second period in immigration detention, IS made multiple attempts at self-harm and suicide in the initial ten days of detention. Multiple Rule 35 reports were triggered and IS was identified as Level 3 AAR, but his detention was nevertheless maintained by the SSHD, in part because of her false belief that his appeal hearing was imminent (notwithstanding that it had been repeatedly pointed out that the scheduled event was only a case management hearing, so that removal was far from imminent). Further details of IS’ detention were not considered at length in the judgment as the SSHD had conceded that his detention was unlawful. 

Tameside Duty of Inquiry

In the landmark case Tameside Metropolitan Borough Council v Secretary of State for Education and Science [1977] AC 1014, Lord Diplock clarified that the starting point for any decision maker is to “ask himself the right question and take reasonable steps to acquaint himself with the relevant information to enable him to answer it correctly” (at 1065B). This question informs the general basis of the duty of inquiry, which has since been articulated by Mr Justice Fordham as a ‘duty of sufficient inquiry’ whereby the ‘public authority must sufficiently acquaint itself with the relevant information, which must fairly be presented and properly addressed’ (Fordham, Judicial Review Handbook at 649). In the years since, the duty of inquiry has come to be governed by the principle of rationality, with courts only intervening where it is considered no reasonable decision maker would have been satisfied that it possessed the necessary information based on the inquiries made (R (Plantagenet Alliance Ltd) v Secretary of State for Justice [2014] EWHC 1662 (Admin)).

In R (Pratima Das) v SSHD (with Mind and Medical Justice Intervening) [2014] EWCA Civ 45, Lord Justice Beatson confirmed that in immigration detention decisions, there was a requirement for the SSHD “conscientiously to make reasonable inquiries as to the physical and mental health of the person who is being considered for detention” [70]. 

Previously, in R (DK) v SSHD [2014] EWHC 3257, Mr Justice Haddon-Cave held that the Tameside duty in such decisions was to be “tailored to the instant case and question” and “reasonable and proportionate” [181]. In that particular case, which also dealt with a claimant suffering from mental health issues, it was held that the “mere possibility that a detainee, or potential detainee, might be suffering from a mental illness” did not trigger the obligation to conduct “a full trawl of…medical records” and a “full up-to-date psychiatric assessment”  [181]. 

Until now, however, it was not clear what the precise scope of the decision maker’s duty was in cases where there was prima facie evidence that a detainee had a severe mental illness. 

An up to date assessment of the scope of this duty was particularly necessary following the Supreme Court’s judgment in R(O) v SSHD [2016] UKSC 19, which confirmed that individuals with severe mental illness are only suitable for detention in very exceptional circumstances, and that in making that determination, the policy requires a “practical enquiry” [31]. However, in AH, Mrs Justice Jefford confirmed that “where the mental health of the detainee is concerned” the inquiry required by AAR demands an assessment including the detainee’s material history as well as up to date information in the form of Rule 35 reports [131]. Such an inquiry had to go beyond a “series of snapshots without context and background” [131]. She clarified that the inquiry in detention decisions hinging on the AAR Policy “were specific to the particular policy but indicative of a detailed inquiry” [131]. 

On the particular facts of the case, it was held that, the SSHD should have considered AH’s previous diagnoses and “whether anything has changed” as part of the larger “context and background” [133, 131]. This more extensive duty of inquiry associated with AAR appears limited to cases dealing with mental health; as Mrs Justice Jefford stated, “where mental health is concerned, an approach which looks solely at current presentation without any regard for past history or diagnoses cannot be justified” [70]. 

Mrs Justice Jefford went on to say that the SSHD has “a duty to seek further information at least if matters arise or events happen that give rise to grounds to review the propriety of detention” [143]. In other words, where there is prima facie evidence of a severe mental illness, there is a duty on the SSHD to engage in further inquiries, including about the individual’s medical history. For now, this more extensive duty does not extend to other cases engaging the AAR Policy, such as individuals assessed at Levels 1 and 2. 

Although the decision in AH does not expand the definition of the Tameside duty per se, it does clarify its temporal scope in immigration detention decisions. Namely, it requires decision makers to conduct something closer to a “trawl” through the detainee’s records where there is prima facie evidence that the detainee could be assessed at Level 2 or 3. 

Interestingly, the judgment in AH aligns with a previous argument put forward by Tim Buley KC and Toby Fisher in a 2014 seminar paper, namely that “where there is a clear prima facie evidence of mental illness… the failure to conduct any assessment of the detainee’s mental health and/or failure to consider any such assessment when making a detention decision may well be an unlawful breach of the Tameside principle” at [21]. AH nevertheless goes a step further, confirming that this duty may require an engagement with the individual’s past medical assessments and current medical assessment as part of “context and background” where there is prima facie evidence of a severe mental illness.

Ananya Kumar-Banerjee is a Lord Denning Scholar of Lincoln’s Inn and BVS student at City, St. George’s.

(Suggested citation: A. Kumar-Banerjee, ‘The Tameside Duty Under the Adults At Risk Policy’, U.K. Const. L. Blog (19th January 2026) (available at https://ukconstitutionallaw.org/))