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Mental Capacity

What is mental capacity?

A person over the age of 16 lacks capacity in relation to a matter if, at the time, they are unable to decide for themselves in relation to that matter because of an impairment of, or a disturbance in the functioning of, the mind or brain.  

The Mental Capacity Act outlines five core principles that underpin work with adults who may lack mental capacity: 

  • Presumption of capacity: Every adult must be assumed to have the capacity to make their own decisions unless it is proven otherwise. 

  • Support to decide: Before concluding that someone lacks capacity, all practicable steps must be taken to help them make the decision for themselves. 

  • Right to make an ‘unwise’ decision: A person is not to be treated as unable to decide merely because others may consider the decision unwise. 

  • Best interests: Any act done or decision made on behalf of a person who lacks capacity must be done or made in their best interests. 

  • Least restrictive option: Before the act is done or the decision is made, consideration must be given to whether the purpose can be as effectively achieved in a way that is less restrictive of the person's rights and freedom of action. 

Capacity is time and decision specific, so staff should work to proactively confirm capacity before decision-making takes place, such as during periods of tenancy enforcement, rent arrears, in resolving anti-social behaviour complaints, and so forth

Last updated: 22 October 2025