Overview
In AG for Northern Ireland [2026] UKSC 16, the Supreme Court has reset the law on deprivation of liberty by unanimously overruling the 2014 Cheshire West judgment and rejecting the long-standing “acid test”, returning to the multi-factorial, context-sensitive approach which aligns with Strasbourg jurisprudence on the Art 5 right to liberty.
The judgment provides important clarification as to the concept of ‘valid consent’, under Art 5, holding that individuals who lack capacity under the Mental Capacity Act (MCA) may nonetheless be able to provide valid consent to liberty restricting measures.
The cumulative effect of the judgment is a substantial narrowing of the scope those who are deprived of their liberty, with immediate implications for medical and social care practitioners.
What has changed
The most striking change is the abolition of the Cheshire West ‘acid test’ (continuous supervision and control and not free to leave) which the Supreme Court held was wrong in principle and inconsistent with Strasbourg authority.
In its place, the Supreme Court has restored the Guzzardi approach, requiring an evaluative assessment of the individual’s “concrete situation”, taking into account factors such as the degree of control, the ability to leave, the duration and effects of restrictions, social contact, the purpose of the arrangements, and their “relative normality”. No single factor is determinative.
Equally important is the reintroduction of a meaningful subjective element. Under Cheshire West, lack of objection and compliance were treated as irrelevant. The Supreme Court has now reversed that position. An individual’s experiences of the arrangements are now central, with objection tending strongly towards a finding of deprivation of liberty, and contentment pointing the other way.
The Supreme Court placed significant weight on coercion as deprivation of liberty is closely linked to situations where the individual’s will is overridden. In the absence of coercion, it will often be difficult to identify a deprivation of liberty.
The Supreme Court emphasised that Art 5 is concerned with physical liberty – freedom to leave a place – rather than broader notions of autonomy, a distinction which underpins the new approach.
The redefinition of consent
The most far-reaching aspect of the decision lies in its treatment of valid consent to liberty restricting measures. The Supreme Court held that valid consent for Art 5 purposes is an autonomous Convention concept, distinct from the MCA test for capacity.
Accordingly, a person may lack capacity to decide on their care arrangements, yet still:
- understand their basic circumstances;
- express wishes or feelings about them; and
- manifest acceptance or contentment.
In such cases, that subjective acceptance may be sufficient to negate the subjective element of a deprivation of liberty.
This represents a decisive move away from the previous orthodoxy that incapacity equates to inability to provide valid consent.
However, the Supreme Court stressed that the assessment must be practical and realistic, and that where there is genuine or serious doubt as to the individual’s wishes or attitude, consent should not be inferred.
Practical Implications
This case provides for a substantial contraction of the application of Art 5. Many individuals previously considered to be deprived of their liberty – particularly in supported living, family placements, and care home arrangements – will now fall outside the scope of Art 5 altogether.
Because the MCA deprivation of liberty safeguards regime is directly tied to Art 5, this narrowing has immediate system-wide consequences, as far fewer cases will now require DoLS authorisation or Court of Protection scrutiny.
The Supreme Court also made clear that many ordinary care settings will fall outside Art 5, for example where a hospital patient is prevented from leaving for their own safety but does not object and is receiving routine treatment.
Safeguarding will increasingly operate through best interests decision-making and Article 8 protections, rather than Article 5 procedural safeguards.
Implications for practitioners
For medical and social care practitioners, the shift is immediate and significant. The Supreme Court has made clear there is no transition period and the acid test in Cheshire West no longer applies with immediate effect.
Assessments must now be holistic and fact-sensitive, focusing on:
- the overall restrictiveness of the regime;
- whether there is coercion or restraint;
- how the arrangements are experienced by the individual; and
- whether there is evidence of objection or contentment.
In particular, the recording and evaluation of wishes and feelings will be important evidence.
The Supreme Court decision introduces new areas of uncertainty. Disputes are likely to arise as to whether apparent compliance reflects genuine acceptance, particularly in cases involving communication difficulties, fluctuating capacity, or the use of medication.
Conclusion
This case marks a decisive move away from a bright-line, protective categorisation approach of Cheshire West towards a more nuanced, person-centered analysis grounded in real experience. While it resolves long-standing practical and resource pressures created by Cheshire West, it replaces them (for the time being at least) with a more uncertain and contested terrain, in which the central question is no longer whether restrictions exist, but how they are experienced by the individual subject to them.
