The Five Principles of the Mental Capacity Act 2005
Section 1 MCA 2005 sets out five core principles that govern every decision about capacity and every act taken on behalf of someone who lacks it — including LPAs, Court of Protection applications, and healthcare decisions.
The Five Principles (s1 MCA 2005)
Presumption of capacity
A person must be assumed to have capacity unless it is established that they lack it (s1(2)).
Solicitors preparing wills and LPAs must assume the client has capacity. Concerns must be investigated — not presumed. The burden lies on those asserting incapacity.
Supported decision-making
A person is not to be treated as unable to make a decision unless all practicable steps to help them do so have been taken without success (s1(3)).
Before concluding someone lacks capacity, ensure: clear communication is used; decisions are timed for when the person is most alert; professional help (interpreter, speech therapist) is engaged if useful.
Right to make unwise decisions
A person is not to be treated as unable to make a decision merely because they make an unwise one (s1(4)).
A testator can leave their estate to a charity instead of their children. A donor can grant an LPA to a friend instead of a solicitor. Unwise choices do not prove incapacity.
Best interests
An act done or decision made for a person who lacks capacity must be in their best interests (s1(5)).
Attorneys and deputies must apply the s4 best interests checklist: consider past wishes, values, and feelings; consult family and carers; not make assumptions based on age, appearance, or behaviour.
Least restrictive option
Before an act or decision is made, regard must be had to whether the purpose can be achieved in a way less restrictive of the person's rights (s1(6)).
An attorney should choose the least intrusive course of action consistent with the person's best interests — e.g. managing specific accounts rather than taking full control of all finances if that suffices.
Frequently Asked Questions
When do the five principles of the MCA 2005 apply?
The five principles in s1 Mental Capacity Act 2005 apply whenever a question arises about whether a person has mental capacity to make a decision, and whenever a decision or act is taken on behalf of a person who lacks capacity. This covers: (1) assessing whether a person has capacity to make a will (testamentary capacity — though the Banks v Goodfellow [1870] common law test, not the MCA statutory test, applies to wills executed under the Wills Act 1837); (2) assessing whether a person has capacity to make an LPA (the MCA statutory capacity test applies here); (3) decisions made by attorneys under a registered LPA; (4) decisions made by deputies appointed by the Court of Protection; (5) healthcare and welfare decisions made for a person who lacks capacity.
How is the MCA 2005 capacity test different from the testamentary capacity test for wills?
The MCA 2005 capacity test under s2 and s3 asks whether a person can understand, retain, use or weigh, and communicate the information relevant to a specific decision. It is a decision-specific, functional test — capacity can be present for one decision (choosing a meal) but absent for another (managing complex investments). In contrast, testamentary capacity for wills is governed by the common law Banks v Goodfellow [1870] test: the testator must understand the nature of making a will and its effects; understand the extent of the property they are disposing of; comprehend and appreciate the claims of those who might expect to benefit; and not be suffering from a disorder of the mind that poisons their affections and distorts their sense of right. The Banks v Goodfellow test is generally considered broader and more flexible than the MCA statutory test. The MCA 2005 statutory test applies to lifetime transactions (making an LPA, entering a contract) but the common law test continues to apply to wills.
How does the best interests principle work for attorneys under an LPA?
When an attorney acts on behalf of a donor who lacks capacity, they must make decisions in the donor's best interests under s4 MCA 2005. The best interests principle is not solely about what the attorney thinks is objectively best — it requires considering: the likelihood the donor will regain capacity and whether the decision can wait; the donor's past and present wishes, feelings, beliefs, and values; the views of family members and carers; and the option least restrictive of the donor's rights. An attorney for property and financial affairs making investment decisions must consider what the donor would have wanted. An attorney for health and welfare decisions must consider the donor's previously expressed wishes (including any advance decision to refuse treatment). Best interests is a holistic balancing exercise, not a simple objective test.
Does the MCA 2005 presumption of capacity affect will-making and LPA creation?
Yes — the presumption of capacity in s1(2) MCA 2005 means that when a person asks a solicitor to make a will or an LPA, the solicitor must start from the assumption that the client has capacity. If there are signs of potential incapacity (e.g., a diagnosis of dementia, significant confusion during instructions), the solicitor should conduct a capacity assessment and may need to seek a formal medical report. Simply having dementia does not mean a person lacks capacity — capacity can fluctuate, and a person may have capacity on a good day. A will made on a lucid day by a person who otherwise lacks capacity can be valid. The MCA 2005 functional test requires a specific assessment at the relevant time for the specific decision being made.
What happens when someone lacks capacity and has not made an LPA?
If a person lacks mental capacity and has not already made a Lasting Power of Attorney (while they had capacity), no one has automatic authority to manage their affairs. The only route is a Court of Protection application for a deputy to be appointed: a property and affairs deputy to manage finances, or a health and welfare deputy to make medical and care decisions. Court of Protection proceedings are considerably more time-consuming and expensive than registering a pre-made LPA — typically taking 6–12 months and costing several thousand pounds. This is why making an LPA while you have capacity is so important. An LPA must be made by the donor while they have capacity — it cannot be created after capacity is lost.
Make Your LPA While You Still Have Capacity
Once capacity is lost, an LPA cannot be made — only a costly Court of Protection deputyship application is possible. The WillSafe kit includes guidance on LPAs alongside will drafting.