The Mental Capacity Act is about giving protection to people who make a decision or do something on behalf of someone who lacks capacity to decide for themselves.  

The person making the decision must comply with the guidance as given in the Code of Practice and must reasonably believe what he/she does or decides is in the best interests of the person concerned.

The Act does not define the Term "best interest" but it gives a helpful checklist of factors in the Code of Practice, which must be considered. The key factors are:

• The person who lacks capacity must be involved as much as possible.
• The person's past and present wishes and feelings must be considered.
• Other people who are involved in the care of the person must be consulted.
• The person making the determination must not make it simply on the basis of the person's age or appearance or the condition of their behaviour.
• You must consider whether the person is likely to have capacity in relation to the matter in question at some time and if so when that it likely to be.