Guide · Health and care · 3 min read
Deciding for someone who can’t
When a person lacks capacity, lasting powers of attorney, and what the court can do when there is none.
In plain English · by laws.sg · not legal advice· Law as at 30 Sep 2026
On this page · 6 parts
The short answer
A person must be assumed to have capacity unless it is established that they lack it, and anything done or decided under the Mental Capacity Act for someone who lacks capacity must be done in their best interests.
While they still have capacity, a person aged 21 or older can make a lasting power of attorney, so that someone they choose can make decisions for them when they no longer can.
When someone lacks capacity
A person lacks capacity about a matter if, at the material time, they are unable to make a decision for themself about it because of an impairment of, or a disturbance in the functioning of, the mind or brain. It does not matter whether the impairment is permanent or temporary.
Mental Capacity Act s 4(1), (2)
A lack of capacity cannot be established merely by a person's age or appearance, or by a condition or behaviour that might lead others to make unjustified assumptions about their capacity.
A person is unable to make a decision if they are unable to understand the information relevant to it, retain that information, use or weigh it in making the decision, or communicate their decision by any means.
The principles
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, and not merely because they make an unwise decision.
Mental Capacity Act s 3(3), (4)
Before something is done or decided for a person who lacks capacity, regard must be had to whether its purpose can be achieved as effectively in a way that is less restrictive of the person's rights and freedom of action.
A lasting power of attorney
A lasting power of attorney lets the person making it confer on a donee, or several donees, authority to make decisions about their personal welfare, their property and affairs, or both, when they no longer have capacity to make those decisions.
It is created only if it is made and registered as the Act requires, and the person making it is 21 or older and has capacity when they execute it. An instrument that does not comply confers no authority.
Mental Capacity Act s 11(2), (3)
A donee may make decisions under it only where the person lacks capacity, or the donee reasonably believes they do.
An undischarged bankrupt cannot be appointed as a donee for decisions about the person's property and affairs.
When there is no lasting power of attorney
If a person lacks capacity about their personal welfare or their property and affairs, the court may make the decision for them by order, or appoint a deputy to make decisions on their behalf.
Mental Capacity Act s 20(1), (2)
In deciding whether appointing a deputy is in the person's best interests, the court has regard to the principles that a decision by the court is preferred to appointing a deputy, and that a deputy's powers should be as limited in scope and duration as is reasonably practicable.
Care and treatment
A person who does an act in connection with the care or treatment of someone, having taken reasonable steps to establish whether they lack capacity and reasonably believing that they lack it and that the act is in their best interests, incurs no liability they would not have incurred if the person had capacity and had consented. This does not exclude liability for negligence in doing the act.
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