1. Legal Framework: Mental Capacity Test (MCA 2005)

Under Section 2–3 MCA 2005, capacity is decided using a two-stage test:

(A) Diagnostic Test

Is there an impairment or disturbance of the mind or brain?

Examples:

• dementia
• learning disability
• brain injury
• mental illness
• intoxication (temporary)

(B) Functional Test

Because of that impairment, can the person:

1. Understand relevant information?
2. Retain it long enough?
3. Use or weigh it in decision-making?
4. Communicate their decision?

If the answer is no to any, the person lacks capacity for that decision.

2. Case Law on Mental Capacity (Detailed)

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

Facts:

• A patient with schizophrenia developed gangrene in his foot.
• Doctors wanted amputation.
• He refused, believing his foot was “not diseased” and that he would heal through meditation.

Legal Issue:

Whether mental illness automatically removes capacity.

Judgment:

The court held:

• Even though C had schizophrenia, he still had capacity.
• He understood information, believed it in his own way, and made a consistent choice.

Key Principle:

A person can have “capacity despite mental illness” if they can:

• understand
• retain
• weigh
• communicate

Importance:

Introduced the idea that:

Diagnosis alone does NOT equal incapacity.

2. Re MB (Medical Treatment: Capacity) [1997]

Facts:

• Pregnant woman needed a caesarean section.
• She had extreme needle phobia, causing panic and refusal of treatment.
• Her condition fluctuated due to fear.

Legal Issue:

Does panic or phobia affect capacity?

Judgment:

The court ruled:

• During panic episodes, she could not weigh information properly.
• Therefore, she temporarily lacked capacity.

Key Principle:

Capacity can be time-specific and situation-dependent.

Importance:

Established:

• Emotional distress can temporarily remove capacity.
• Capacity is not static.

3. Masterman-Lister v Brutton & Co [2002]

Facts:

• Concerned whether a claimant had capacity to manage litigation decisions.
• The issue was whether he could understand legal proceedings.

Legal Issue:

What is the correct standard for capacity in legal decisions?

Judgment:

The Court of Appeal held:

• The test is whether the person can understand, process, and weigh relevant information for the specific decision.
• Capacity is decision-specific, not global.

Key Principle:

There is no single “all-or-nothing” capacity status.

Importance:

This case heavily influenced MCA 2005 principles:

• “Issue-specific capacity” became central law.

4. Re T (Adult: Refusal of Treatment) [1992]

Facts:

• A pregnant woman refused a blood transfusion due to religious influence.
• She had been under pressure from her mother (a Jehovah’s Witness).
• After separation from her mother, she changed her mind.

Legal Issue:

Was her refusal valid and autonomous?

Judgment:

The court held:

• She lacked capacity at the time of refusal due to undue influence and impaired judgment.
• The refusal was not fully voluntary.

Key Principle:

Capacity can be undermined by:

• coercion
• emotional domination
• undue influence

Importance:

Shows capacity is not just cognitive but also about free decision-making.

5. PC v City of York Council [2013]

Facts:

• Concerned a man with autism and learning difficulties.
• He was restricted by local authority measures for his own safety.
• The question was whether he had capacity in certain areas.

Legal Issue:

How should capacity be assessed in borderline intellectual functioning cases?

Judgment:

The court clarified:

• The assessment must focus strictly on the MCA 2005 functional test.
• Capacity must not be confused with “unwise decisions”.

Key Principle:

“An unwise decision does NOT mean lack of capacity.”

Importance:

Reinforced statutory principle:

• People can make risky or unusual choices and still be competent.

6. A Local Authority v JB [2021]

Facts:

• Concerned a man with learning disability.
• Issue: whether he had capacity to consent to sexual relations.
• Risk arose due to misunderstanding of consent and risks of sexual activity.

Legal Issue:

What does capacity mean in sexual decision-making?

Judgment:

The Supreme Court held:

• A person must understand:
  • the physical act
  • consent of the other person
  • risks of pregnancy and STIs
• Capacity requires understanding reciprocal consent, not just physical mechanics.

Key Principle:

Capacity standards vary depending on the seriousness and context of decision.

Importance:

This case modernised capacity law in sensitive areas like sexuality.

3. Key Themes from These Cases

Across all cases, courts consistently emphasize:

1. Decision-specific capacity

A person may have capacity for one decision but not another.

2. Time-specific capacity

Capacity can fluctuate (e.g., panic, illness, intoxication).

3. Function over diagnosis

Mental illness or disability alone is not enough.

4. Respect for autonomy

People can make unwise or risky decisions and still be capable.

5. Protection against impairment effects

Undue influence, fear, or misunderstanding can invalidate consent.

4. Simple Summary

Mental Capacity Assessment is not about labeling someone as “capable” or “incapable” in general. Instead, it asks:

“Can this person make THIS decision, at THIS time, with THIS information?”

Case law ensures the law protects both:

• autonomy (freedom of choice)
• safety (protection when decision-making is impaired)