Capacity Case Law: Ten Essential Judgments Anyone Who Assesses Mental Capacity Should Know – and Why

Ten pivotal cases have shaped the legal framework and clinical interpretation of mental capacity in England and Wales. Whether you're a seasoned expert witness or newly involved in capacity assessments, these decisions provide foundational insight into how courts interpret and apply the Mental Capacity Act 2005 (MCA) in complex real-world scenarios.

1. Re C (Adult: Refusal of Medical Treatment) [1994] 1 WLR 290

• Why it matters: Re C laid the groundwork for the functional approach to capacity, establishing that capacity is not negated by mental illness or irrational decisions. It introduced the key components later codified in the MCA.
• Case in brief: Mr. C, a psychiatric inpatient with paranoid schizophrenia, refused a life-saving amputation. The court found him capable of making the decision, as he could understand, retain, and weigh the relevant information. The case marked a significant move away from paternalism toward respect for individual autonomy.

2. Masterman-Lister v Brutton & Co [2003] 1 WLR 1511

• Why it matters: This case established the principle that capacity is decision- and time-specific, and that the ability to act in one’s best interests is not required for capacity.
• Case in brief: A personal injury litigant’s historic litigation capacity was challenged. The Court of Appeal ruled that litigation capacity depends on the ability to understand proceedings and make decisions with support. This case prefigured the MCA’s approach and remains central in cases involving litigation capacity.

3. Re MB (Medical Treatment) [1997] 2 FLR 426

• Why it matters: This case reinforced the principle that irrationality does not equate to incapacity and that temporary impairments, such as panic, can be capacity-limiting.
• Case in brief: A pregnant woman refused a Caesarean due to needle phobia. The court found her temporarily incapacitated due to panic, not mental disorder. The decision affirmed that capacity assessments must account for the context and temporal factors.

4. Re MM (An Adult) [2007] EWHC 2003 (Fam)

• Why it matters: Re MM highlighted that vulnerability and perceived risk should not overshadow a person’s capacity. The court advocated for a realistic threshold of decision-making ability.
• Case in brief: A woman with learning disabilities wanted to live with her partner. Despite safeguarding concerns, the court found she had capacity to make that decision. It reiterated that autonomy must prevail unless the MCA criteria are clearly not met.

5. A Local Authority v JB [2021] UKSC 52

• Why it matters: This Supreme Court case clarified that the capacity to consent to sex includes the ability to understand the concept of mutual consent.
• Case in brief: JB, a man with autism and learning disability, wished to pursue intimate relationships. The court concluded that understanding the necessity for the other party’s consent is integral to capacity in this domain. It extended the 'use or weigh' limb to encompass relational and ethical awareness.

6. Derbyshire County Council v Grundy [2025] EWCOP 1 (T1)

• Why it matters: The case distinguished between executive dysfunction and incapacity, reaffirming that repeated non-compliance alone does not demonstrate lack of capacity.
• Case in brief: Mr. Grundy breached an injunction prohibiting contact with a vulnerable person. Though he exhibited possible executive dysfunction, the court found this did not render him incapable of understanding or weighing information about the injunction. The ruling upheld the presumption of capacity and cautioned against conflating disobedience with cognitive incapacity.

7. PC and NC v City of York Council [2013] EWCA Civ 478

• Why it matters: This case reinforced the strength of the presumption of capacity and warned against value-laden judgments.
• Case in brief: A woman wished to live with her partner, despite safeguarding concerns. The Court of Appeal found that her decision, although risky, did not show incapacity. The decision cautioned against substituting professional views for legally grounded capacity assessments.

8. Kings College Hospital NHS Foundation Trust v C and V [2015] EWCOP 80

• Why it matters: This case drew attention to fluctuating capacity and the need to identify the timing of decisions with precision.
• Case in brief: A woman refused dialysis, prompting a question of capacity. The court found her capacity fluctuated and stressed that assessments must capture the person’s abilities at the time the decision is made, not retrospectively.

9. York City Council v C [2013] EWCA Civ 478

• Why it matters: The judgment clarified the burden of proof required to rebut the presumption of capacity and reaffirmed the need for both elements of the MCA test.
• Case in brief: The local authority failed to prove that a woman lacked capacity to make decisions about her residence. The court insisted on clear evidence of both a mental impairment and a causal link to inability to decide.

10. LBX v K, L and M [2013] EWHC 3230 (Fam)

• Why it matters: This case focused on the rigour required in expert capacity assessments and criticised the use of vague or formulaic reasoning.
• Case in brief: The court reviewed capacity assessments in the context of family disputes and found them wanting. The judge called for structured, transparent reasoning that explicitly applies the statutory criteria.

These ten cases provide essential guidance for anyone undertaking capacity assessments. Together, they establish that capacity is functional, dynamic, specific to the decision and time, and must be approached with care, clarity, and respect for autonomy.