Capacity is the ability to make decisions for oneself.
A person has capacity when they can go through the process of making their own decisions by:
understanding the information and choices presented
weighing up the information to determine what the decision will mean for them
communicating that decision.
If a person is unable to follow this process and make their own decisions, that person is said to lack capacity.
The Capacity Toolkit, produced by the Department of Attorney General and Justice, provides information about capacity and how to decide if a person has the capacity to make their own decisions.