Capacity

Capacity is the mental ability to understand the nature and effect of a decision, retain and weigh the relevant information, and communicate a choice. It underpins almost every estate-planning document: you must have capacity to make a valid Power of Attorney, appoint an Enduring Guardian, or sign a Will (where it is called testamentary capacity). Capacity is decision-specific and time-specific — a person may have enough capacity for a simple decision but not a complex one, and it can fluctuate day to day. The law presumes adults have capacity unless there is evidence otherwise.

In practice, capacity is assessed at the moment a document is signed, and a doctor's report is often obtained where there is any doubt or early cognitive decline. Example: Because her father showed early signs of dementia, Hannah arranged a GP assessment confirming he still had capacity before he signed his new Enduring Power of Attorney. If capacity is later disputed, contemporaneous medical evidence is often decisive — for both Powers of Attorney and a statutory Will.