Assessments

Mental Capacity Assessment for Social Workers UK

January 2025•13 min read

Understanding the Mental Capacity Act 2005

The Mental Capacity Act 2005 (MCA) provides the legal framework for assessing whether a person has the mental capacity to make specific decisions, and for making decisions on behalf of those who lack capacity. As a social worker, understanding and correctly applying the MCA is essential for ethical, lawful practice.

The Act applies to anyone aged 16 or over in England and Wales. It is built on five statutory principles that must guide all assessments and decisions.

The Five Principles

  1. Presumption of capacity: Every adult has the right to make their own decisions and must be assumed to have capacity unless proven otherwise
  2. Support to decide: All practicable steps must be taken to help a person make their own decision before concluding they lack capacity
  3. Unwise decisions: A person is not to be treated as lacking capacity merely because they make an unwise decision
  4. Best interests: Any decision made for someone who lacks capacity must be in their best interests
  5. Least restrictive: Any action taken must be the least restrictive of the person's rights and freedoms

Key principle: Capacity is decision-specific and time-specific. A person may have capacity for some decisions but not others, and capacity may fluctuate over time.

When to Assess Capacity

A capacity assessment is needed when:

  • There is reason to believe the person may lack capacity for a specific decision
  • A significant decision needs to be made
  • The person's capacity to make the decision is in doubt
  • There is an impairment or disturbance in the functioning of the mind or brain

Examples of decisions requiring capacity assessment:

  • Agreeing to care and support services
  • Moving to residential care
  • Managing finances
  • Medical treatment decisions
  • Deciding where to live
  • Contact with family members

The Two-Stage Test

Capacity assessment involves a two-stage test that must be applied to the specific decision at hand:

Stage 1: Diagnostic Test

Is there an impairment of, or disturbance in the functioning of, the person's mind or brain?

This could include:

  • Dementia
  • Learning disability
  • Mental health conditions
  • Brain injury
  • Stroke
  • Delirium
  • Effects of substance misuse

If there is no impairment or disturbance, the person has capacity (even if they make unwise decisions).

Stage 2: Functional Test

If there is an impairment or disturbance, does it mean the person is unable to make the specific decision at the specific time?

A person is unable to make a decision if they cannot:

  1. Understand the information relevant to the decision
  2. Retain that information long enough to make the decision
  3. Use or weigh the information as part of decision-making
  4. Communicate their decision (by any means)

If the person fails any one of these four elements, they lack capacity for that decision.

Practical Assessment Steps

Before the Assessment

  • Identify the specific decision to be made
  • Consider the timing - is this the best time to assess?
  • Gather relevant information about the person's condition
  • Plan how to communicate effectively
  • Consider who should be present (supporter, interpreter)
  • Prepare information in accessible format if needed

During the Assessment

  • Explain what you're doing and why
  • Provide information about the decision in simple terms
  • Use appropriate communication methods
  • Give the person time to process information
  • Check understanding by asking them to explain back
  • Explore their reasoning - how are they weighing the options?
  • Ask open questions rather than leading ones

The Four Abilities in Practice

Understanding

Can they understand the key information about the decision?

  • What the decision is
  • Why it needs to be made
  • The likely consequences of deciding each way
  • The likely consequences of not deciding

Retaining

Can they hold the information long enough to make the decision?

  • They don't need to remember forever
  • Using memory aids is acceptable
  • Only need to retain long enough to use the information

Using or Weighing

Can they weigh up the pros and cons?

  • Can they consider different options?
  • Can they balance risks and benefits?
  • Does their condition prevent them from weighing up?
  • (Note: they may weigh differently than you would - that's okay)

Communicating

Can they communicate their decision?

  • By any means - speech, signing, gestures, behaviour
  • Consider communication aids and support
  • This is rarely the reason for lacking capacity

Recording the Assessment

MENTAL CAPACITY ASSESSMENT Person: [Name, DOB] Date of Assessment: [Date] Assessor: [Name, Role] DECISION TO BE MADE [Clearly state the specific decision] STAGE 1: DIAGNOSTIC TEST Is there an impairment of, or disturbance in the functioning of, the person's mind or brain? [Yes/No] If yes, what is the nature of the impairment? [Describe the diagnosis or condition] STAGE 2: FUNCTIONAL TEST Understanding Information provided: [What information was given about the decision] Evidence of understanding: [How the person demonstrated understanding or lack of understanding] Retaining Evidence of ability to retain: [How the person demonstrated ability or inability to retain] Using or Weighing Evidence of ability to use/weigh: [How the person demonstrated ability or inability to weigh the information] Communicating Evidence of ability to communicate: [How the person communicated their views] CONCLUSION Does the person have capacity to make this decision? [Yes/No] Reasoning: [Clear explanation of how you reached this conclusion, with reference to the evidence above] Signature: _______________ Date: _______________

What If the Person Lacks Capacity?

If you conclude the person lacks capacity:

  • The decision must be made in their best interests
  • Consider their wishes, feelings, beliefs, and values
  • Consult relevant others (family, carers, professionals)
  • Consider whether capacity might be regained
  • Choose the least restrictive option
  • Document your best interests decision-making

Common Mistakes

  • Assuming incapacity: Based on diagnosis, age, or appearance
  • Not being decision-specific: Assessing "capacity" generally rather than for a specific decision
  • Not supporting decision-making: Not taking all practicable steps to help the person decide
  • Confusing unwise with incapable: People can make unwise decisions and have capacity
  • Poor timing: Assessing at the wrong time of day or when the person is unwell
  • Leading questions: Asking questions that suggest the "right" answer
  • Inadequate recording: Not documenting the evidence for the conclusion

Remember: An unwise decision is not the same as an incapable decision. If the person understands, retains, uses/weighs, and communicates, they have capacity - even if their decision seems unwise to you.

Fluctuating Capacity

Some conditions cause capacity to fluctuate:

  • Delirium
  • Some mental health conditions
  • Early dementia
  • Medication effects

Consider:

  • Can the decision wait until a time of better capacity?
  • Is there a pattern to the fluctuation?
  • What time of day is the person at their best?
  • What support would maximise capacity?

Document Capacity Assessments Clearly

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Conclusion

Mental capacity assessment is a fundamental skill for social workers. By applying the two-stage test systematically, supporting people to make their own decisions where possible, and documenting your assessment clearly, you ensure that practice is both lawful and ethical.

Always remember: capacity is decision-specific and time-specific. An unwise decision does not equal incapacity. And the starting point is always the presumption that the person has capacity unless proven otherwise.