The Mental Capacity Act 2005 and Lasting Power of Attorney
The legal framework that makes LPAs possible — and the principles that protect everyone involved.
Written by Anthony Dalton · Reviewed by James Tyrrell · Last reviewed
Every Lasting Power of Attorney in England and Wales exists because of one piece of legislation: the Mental Capacity Act 2005 (MCA). This Act created the modern LPA system, replacing the older Enduring Power of Attorney with a more comprehensive and protective framework. It also established the five principles that every attorney must follow when making decisions on someone else's behalf.
At a glance
- The Mental Capacity Act 2005 is the law that created the modern LPA system in England and Wales
- It establishes five legally binding principles, including the presumption of capacity and the best interests duty
- Capacity is assessed decision by decision — not as an all-or-nothing judgement
- The Act also created the Court of Protection, the Office of the Public Guardian, and advance decisions to refuse treatment
Understanding the MCA is not just academic — it has real consequences for how LPAs are created and used.
What the Mental Capacity Act Does
The Mental Capacity Act 2005 came into force in October 2007 and applies to England and Wales. It provides a comprehensive legal framework for making decisions on behalf of people aged 16 and over who lack the mental capacity to make those decisions themselves. The Act covers a wide range of situations, from everyday choices about personal care to major financial and medical decisions.
The Act established several key mechanisms, including Lasting Powers of Attorney, the Court of Protection in its modern form, the role of the Office of the Public Guardian, Independent Mental Capacity Advocates (IMCAs), and advance decisions to refuse treatment. Together, these create a system designed to protect vulnerable people while respecting their autonomy as much as possible.
The Five Statutory Principles
At the heart of the Mental Capacity Act are five statutory principles that guide every decision made under its authority. These principles are legally binding and apply to anyone making decisions on behalf of someone who may lack capacity — including LPA attorneys. Understanding these principles is crucial.
Presumption of Capacity
Every person is assumed to have mental capacity unless it is established otherwise. You cannot assume someone lacks capacity simply because of their age, appearance, condition, or behaviour. This principle protects against discrimination and ensures that people are not treated as incapable without proper assessment.
Support to Make Decisions
Before concluding that someone lacks capacity, all practicable steps must be taken to help them make the decision themselves. This might include providing information in simpler language, using visual aids, choosing a time of day when the person is most alert, or involving someone they trust in the discussion.
Right to Make Unwise Decisions
A person is not to be treated as lacking capacity merely because they make a decision that others consider unwise. Everyone has the right to make choices that others might disagree with. Making an unconventional or risky decision does not, by itself, indicate a lack of mental capacity.
Best Interests
Any act done or decision made on behalf of a person who lacks capacity must be done in their best interests. This is the overriding principle that governs all decisions made by attorneys, deputies, and healthcare professionals under the Act.
Least Restrictive Option
Before making a decision or taking action, consideration must be given to whether the desired outcome can be achieved in a way that is less restrictive of the person's rights and freedom. The least intrusive intervention that meets the person's needs should always be preferred.
Key point: These five principles are not optional guidance — they are legal requirements. Every decision your attorney makes under an LPA must be consistent with these principles, and failure to follow them could result in the attorney being investigated or removed.
The Two-Stage Test for Assessing Mental Capacity
The Mental Capacity Act sets out a clear two-stage test for determining whether someone lacks mental capacity to make a particular decision:
Stage 1: Is there an impairment of, or disturbance in, the functioning of the person's mind or brain? This could be caused by dementia, a stroke, a brain injury, a mental health condition, learning disability, substance misuse, or any other condition affecting brain function.
Stage 2: Does that impairment or disturbance mean the person is unable to make the specific decision at the relevant time? A person is unable to make a decision if they cannot do one or more of the following:
- Understand the information relevant to the decision
- Retain that information long enough to make the decision
- Use or weigh that information as part of the decision-making process
- Communicate the decision (by any means, including sign language, gestures, or blinking)
Crucially, capacity is assessed on a decision-by-decision basis. A person may lack capacity to make complex financial decisions but retain capacity to decide what they want to eat or who they want to visit them. Capacity can also fluctuate — someone might have capacity at certain times of day but not others, or during periods of better health. For more on how capacity relates to LPAs, see our guide on LPAs and mental capacity.
Best Interests Decisions in Practice
When an attorney makes a decision under an LPA, they must follow the best interests checklist set out in Section 4 of the Mental Capacity Act. This is not simply a matter of doing what the attorney thinks is best. The checklist requires the decision-maker to:
- Consider whether the person is likely to regain capacity and whether the decision can wait
- Encourage the person to participate in the decision as far as possible
- Consider the person's past and present wishes, feelings, beliefs, and values
- Take into account the views of anyone the person has asked to be consulted, or anyone caring for them or interested in their welfare
- Avoid being motivated by a desire to bring about the person's death (when the decision relates to life-sustaining treatment)
This framework ensures that decisions are not made in a vacuum. The attorney must actively seek out and consider the donor's known wishes and the views of people close to them. It is a thorough and considered process, not a casual judgement call.
The Role of the Court of Protection
The Mental Capacity Act established the Court of Protection as a specialist court to deal with all matters relating to people who lack capacity. The court has broad powers, including the ability to make decisions on behalf of people who lack capacity, appoint deputies, determine whether someone has capacity, and make declarations about the lawfulness of actions taken under the Act.
In relation to LPAs specifically, the Court of Protection can determine whether an LPA is valid, remove an attorney who is acting improperly, give directions about how an LPA should be used, and resolve disputes between attorneys or between attorneys and other interested parties. For more detail on the court, see our guide on the Court of Protection.
What This Means When You Create or Use an LPA
When you make an LPA, you are working within the framework the MCA provides. Your attorney will be bound by its principles and accountable under its provisions.
If you are choosing an attorney, you should be confident that they understand these principles and will apply them conscientiously. If you are creating an LPA for a family member who may be in the early stages of a condition like dementia, it is important to act while they still clearly have capacity under the Act's definition. If there is any doubt, a capacity assessment from a medical professional can provide evidence that the person had capacity when the LPA was created. For guidance on timing, see our guide on when it is too late to make an LPA.
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Key Takeaways
- The MCA created the LPA system — without the Mental Capacity Act 2005, Lasting Powers of Attorney would not exist in their current form
- Five principles are legally binding — presumption of capacity, support to decide, right to unwise decisions, best interests, and least restrictive option must all be followed
- Capacity is decision-specific — a person may lack capacity for one type of decision while retaining it for others
- Best interests is not personal preference — attorneys must follow a structured checklist considering the donor's wishes, feelings, beliefs, and values
- The Court of Protection resolves disputes — it can determine capacity, remove attorneys, and make binding decisions when disagreements arise
Answers to Questions We Get Asked
What are the five principles of the Mental Capacity Act 2005?
The five principles are: presumption of capacity, support to make decisions, the right to make unwise decisions, acting in the person's best interests, and choosing the least restrictive option. These are legally binding and must be followed by anyone making decisions on behalf of someone who lacks capacity.
When did the Mental Capacity Act 2005 come into force?
The Mental Capacity Act 2005 came into force in October 2007. It applies to England and Wales and replaced the older Enduring Power of Attorney system with the modern Lasting Power of Attorney framework.
Is mental capacity assessed as all-or-nothing?
No. Capacity is assessed on a decision-by-decision basis. A person may lack capacity to make complex financial decisions but retain capacity to decide everyday matters like what to eat. Capacity can also fluctuate, meaning someone might have capacity at certain times but not others.
This guide was last reviewed and updated on . Information is based on current legislation and OPG guidance for England and Wales.
Official Guidance
Further reading from GOV.UK
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