A jargon-free guide to Capacity Law.

Mental capacity is governed by the Mental Capacity Act 2005, which applies in England and Wales to anyone aged 16 or over. The purpose of the law is to set out when a person can make their own decisions and how those decisions should be approached if capacity is in doubt. Capacity is not a label that applies to a person as a whole. Instead, the law looks at whether someone can make a specific decision, at the time it needs to be made.

In legal terms, a person has mental capacity if they are able to understand the information relevant to the decision, remember that information long enough to decide, weigh it up as part of the decision making process, and communicate their decision in some way. All four of these elements matter. Difficulty with just one part may mean a person lacks capacity for that particular decision.

The law starts from a very clear position: every adult is assumed to have capacity. This presumption stands unless it is shown, using the legal test, that capacity is lacking. Importantly, the law also says that people must be given all reasonable help to make their own decisions before anyone concludes that they cannot do so. This might include explaining information in a simpler way, giving more time, or using visual aids or support.

Capacity is not lost simply because someone makes a choice that others disagree with. The law is explicit that a person is allowed to make decisions that seem unwise, unusual, or risky, as long as they understand what they are deciding. Capacity is about ability, not outcomes.

There is no single person or authority who decides capacity in every case. Instead, capacity is assessed by whoever is responsible for making or acting on the decision at hand. This might be a doctor, nurse, social worker, or solicitor, depending on the situation. The assessment follows a two stage process. First, the assessor considers whether there is an impairment or disturbance of the mind or brain. Second, they look at whether that impairment means the person is unable to make the specific decision in question. Both stages must be satisfied.

When a person is found to lack capacity for a decision, the law requires that any decision made for them, under a Power of Attorney for example, must be made in their best interests. This is a legal test, not a personal opinion. It requires the decision maker to think about the person’s past and present wishes, their beliefs and values, and any other factors they would be likely to consider themselves. Where possible, the person should still be involved in the process. The law also requires that decisions are made in the least restrictive way, interfering as little as possible with the person’s rights and freedom.

Overall, mental capacity law is designed to be practical and fair. It focuses on real decisions, real ability, and real evidence, rather than assumptions or labels. Understanding these legal principles allows decisions to be made properly, respectfully, and in line with the law, even in situations where time or clarity is limited.

For specific legal advice on how people can provide for their wishes when they no longer have capacity to make decisions, please call us on 0203 835 4964 or email dmillward-stone@scomo.com.