Who decides what is in someone’s best interests?

"Best interests" under the Mental Capacity Act 2005 is a process as much as an outcome. There is no single decision-maker for all purposes: it is whoever is making the specific decision — the clinician proposing treatment, the social worker arranging a placement, or an attorney or deputy acting within their authority.

What must be taken into account

• The person’s wishes, feelings, values and beliefs, past and present. Past wishes carry serious weight but are not automatically decisive — a previously expressed wish to die at home, for example, may have to be balanced against clinical needs that make home care unsafe.
• Present-day expressions. Someone who lacks capacity to make the decision may still show assent, dissent or distress, and those reactions must be considered.
• The views of family, carers and anyone interested in their welfare, which the decision-maker is required to seek out.
• The least restrictive option that achieves the purpose — a smaller intervention that works is preferred to a larger one.

Best interests is broader than clinical benefit alone: relationships, dignity, routine and what mattered to the person before all belong in the analysis.

Being heard as a family member

The MCA Code of Practice requires decision-makers to consult those caring for or interested in the person’s welfare, so a close relative cannot normally be shut out. If you are being excluded, say so in writing to the professional concerned and escalate through the complaints process. Where the person lacks capacity and has no family or friends to consult, an Independent Mental Capacity Advocate must be instructed for serious medical treatment decisions and care home moves.

When people disagree

The decision-maker must weigh all views but is not bound by any one family member’s preference. Where families are split, a clinical ethics consultation or mediation often resolves matters faster than confrontation. If a serious decision remains genuinely disputed, the Court of Protection can make a binding determination.

Practical advice: record what the person said about their wishes while they could express them, ask for the decision and its reasons in writing, and ask which alternatives were considered and why they were rejected. Those questions do more to improve a decision than any argument about who is in charge.