Whenever a person is supporting another person to make decisions about their care or treatment, they must apply the following five key legal principles:
| Principle One | You must always start with the assumption that a person has the mental capacity to make the decision in question |
| Principle Two | All practical steps must be taken to assist a person to make a decision, before a decision is made on their behalf |
| Principle Three | A person who makes an unwise decision must not be presumed to lack mental capacity because of this |
| Principle Four | Any act done on behalf of a person who lacks capacity must be undertaken in the person's best interests |
| Principle Five | Before any action or decision is taken consideration must be given to whether the outcome can be effectively achieved in a less restrictive way |
The first three principles are focussed on empowering or enabling the person to make their own decisions.
The last two principles are concerned with how decisions are to taken on a person's behalf
The Mental Capacity Act Code of Practice provides guidance on how decisions should be made if a person lacks the mental capacity to make these for themselves.