The End of the ‘Acid Test’: Supreme Court Recasts the Law on Deprivation of Liberty

Court of Protection, Health & Social Care, Judicial Review & Public Law, Local Government

In constitutionally significant decision, the Supreme Court has fundamentally reshaped the law on deprivation of liberty under article 5 ECHR, overruling the “acid test” established in a previous decision more than a decade ago.

The judgment will have considerable consequences for health and social care practice throughout the United Kingdom, particularly for those responsible for supported living arrangements, care planning, and deprivation of liberty authorisations.

The reference, brought by the Attorney General for Northern Ireland, concerned whether proposed revisions to Northern Ireland’s Deprivation of Liberty Safeguards (“DOLS”) Code of Practice would be incompatible with Article 5 of the European Convention on Human Rights. The proposed revisions sought to recognise that some individuals who lack legal capacity under domestic legislation may nevertheless be capable of giving “valid consent” to their care and living arrangements through the expression of wishes and feelings.

The Supreme Court has held that the proposed approach was lawful. In doing so, the Court expressly overruled P v Cheshire West and Chester Council; Surrey County Council v P [2014] UKSC 19.

David Welsh, a member of chambers, was instructed by the Mental Welfare Commission for Scotland, one of the interveners in the proceedings.

Background: the legacy of Cheshire West

The practical significance of the decision can only be understood against the background of Cheshire West. In that case, the Supreme Court adopted what Baroness Hale described as the “acid test” for deprivation of liberty: whether a person was subject to “continuous supervision and control” and “not free to leave”.

Crucially, the Court in Cheshire West treated factors such as compliance, contentment, normality of the setting, and the benevolent purpose of the arrangements as irrelevant. Baroness Hale’s well-known observation that “a gilded cage is still a cage” became the defining statement of the modern law.

The consequences were profound. Following Cheshire West, very large numbers of individuals in care homes, hospitals, supported living placements and family settings came to be regarded as deprived of their liberty for Article 5 purposes, even where they appeared content with their arrangements and were receiving supportive care in ordinary domestic environments.

The evidence before the Court in the present reference illustrated the scale of the issue. DOLS applications in England and Wales rose from around 13,700 before Cheshire West to more than 330,000 annually by 2023/24, producing substantial backlogs, significant resource burdens, and repeated concerns about the practical operation of the safeguarding regime.

The issue before the Court

The Northern Ireland Minister of Health proposed revising the statutory Code of Practice issued under the Mental Capacity Act (Northern Ireland) 2016. The revised approach would permit decision-makers, in some circumstances, to conclude that an individual lacking formal legal capacity nevertheless validly consented to their confinement through positive expressions of wishes and feelings.

The Attorney General argued that Cheshire West had misinterpreted Strasbourg jurisprudence by treating lack of domestic mental capacity as automatically equivalent to absence of valid consent under article 5. A number of interventions were permitted by the Court. Scotland’s Lord Advocate broadly supported the revised approach, as did the Mental Welfare Commission for Scotland. The Secretary of State for Health and Social Care argued that Cheshire West had departed too far from European authority by reducing a multifactorial assessment to a binary “acid test”.

By contrast, the Official Solicitor and the charities Mind, Mencap and the National Autistic Society expressed serious concerns regarding the removal of safeguards for vulnerable individuals.

The Court’s reasoning

The Supreme Court conducted an extensive review of Strasbourg authority and concluded that the European Court of Human Rights had never adopted the rigid “acid test” articulated in Cheshire West. Instead, Strasbourg jurisprudence consistently required a “multifactorial” assessment of the person’s “concrete situation”, including:

• the type and degree of restriction;
• duration and effect;
• the manner of implementation;
• the purpose of the arrangements;
• the individual’s perceptions and wishes; and
• whether there was valid consent.

Importantly, the Court held that “valid consent” for Article 5 purposes is an autonomous Convention concept and is not synonymous with legal capacity under domestic mental capacity legislation.  Therefore, a person may lack capacity to make formal decisions under the MCA framework while still possessing sufficient understanding to express meaningful acceptance of their living arrangements.

The Court accepted that the views and wishes of individuals in care should, where possible, be respected as an aspect of dignity and autonomy protected by the Convention itself.

Overruling Cheshire West

Having concluded that Cheshire West represented a departure from Strasbourg authority, the Supreme Court invoked the 1966 Practice Statement and formally overruled it. That is unusual in and of itself.

The Court accepted that the practical consequences of Cheshire West were highly significant. The judgment refers repeatedly to the administrative strain created by the post-Cheshire West regime, including excessive procedural burdens, diversion of resources, and distress caused by intrusive assessments in cases where individuals appeared settled and content in their placements.

The Court was particularly concerned that Article 5 safeguards had expanded beyond situations closely analogous to actual detention and had come to encompass a very wide range of ordinary supportive care arrangements.

The Court concluded that Article 5 does not require that all such arrangements be treated as deprivations of liberty merely because restrictions exist.

What does the new approach mean?

The immediate effect (and it is important to note that the decision is immediately effective) of the judgment is to replace the Cheshire West “acid test” with a broader contextual assessment. Continuous supervision and a lack of freedom to leave remain important factors, but they are no longer determinative on their own.

Instead, Courts and practitioners will now need to examine the overall reality of the person’s situation, including whether the individual positively accepts or wishes to remain in the placement. The Court stressed, however, that mere acquiescence will not be sufficient. Careful assessment will still be required, particularly for individuals with communication difficulties or fluctuating wishes and feelings. Where there is doubt, the legal safeguards remain the appropriate option.

The judgment repeatedly acknowledges the evidential and ethical complexity of assessing “positive consent” in practice. Concerns raised by the charities regarding masking behaviour, suggestibility, fear of consequences, and communication barriers were treated seriously by the Court.

Guidance and implementation remain awaited

The Court recognises that additional detailed guidance will be required. The judgment also noted that the implications of the decision may extend beyond community settings into hospitals, care homes, supported living arrangements, and private domestic placements.

Much will therefore depend on how future guidance frames concepts such as:

• “positive attitude” toward care arrangements;
• tacit versus active consent;
• fluctuating wishes;
• evidential thresholds; and
• appropriate review mechanisms.

Equally important will be the manner in which Courts and tribunals implement the new framework in practice. There is likely to be a period of considerable adjustment as health bodies, local authorities, care providers, practitioners and judges work through the implications of the decision.

A decision of constitutional and practical significance

The judgment is one of the most important mental capacity decisions in recent years. It substantially redefines the legal architecture surrounding deprivation of liberty throughout the United Kingdom and recalibrates the relationship between autonomy, protection, and state intervention.

For some, the decision will be welcomed as a long-overdue correction to an over-expansive interpretation of article 5 which generated unsustainable administrative consequences and unnecessary intrusion into family and care arrangements.  For others, concerns will remain that narrowing the scope of deprivation of liberty risks weakening protections for highly vulnerable individuals.

What is clear is that the practical impact of the decision will depend heavily on the quality of forthcoming guidance and on the sensitivity with which courts and practitioners apply the new multifactorial test in individual cases.

In the meantime, all those involved in health and social care law will need to follow developments closely. Our Court of Protection barristers would be happy to assist anyone looking for advice on any of the matters raised in the decision should contact us via email or via phone on 020 7242 4986.

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