**Capacity** (noun) — The mental and legal ability to understand the nature and consequences of one's actions and decisions, particularly in making legal documents or entering into contracts.
Capacity means having the mental ability to understand what you're doing when you make legal decisions. It's about whether you can comprehend the choice you're making and what it means for you.
Different decisions require different levels of capacity. The standard for making a will is relatively low—you need to understand you're deciding who gets your property when you die. Making complex business decisions requires higher capacity. Generally, the law presumes adults have capacity unless proven otherwise.
Capacity can fluctuate. Someone might have good days and bad days, particularly with conditions like dementia. This is why significant legal documents are often prepared when the person is having a clear period, sometimes with medical professionals confirming capacity at that moment.
⏱ When you'll encounter this term
Capacity becomes relevant when someone questions whether a person understood what they were doing when they signed a will, power of attorney, or other legal document. If someone lacked capacity, the document might be invalid.
Common capacity challenges arise with elderly people making late-life changes to estate plans, people with dementia creating new wills, or individuals signing documents while on medication that affects cognition. Courts look at whether the person understood what they were signing at that specific moment, not their general mental state.
Doctors, lawyers, and witnesses often document capacity when preparing legal documents for someone whose mental state might be questioned. Notes about the person's awareness, understanding, and behavior during signing help defend against later challenges. If capacity is questionable, the person should undergo formal capacity assessment before signing important documents.
**Related terms:** [Testamentary Capacity](/dictionary/testamentary-capacity), [Mental Capacity](/dictionary/mental-capacity), [Competent](/dictionary/competent)
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"Mum had dementia but her doctor assessed that she had capacity to make a will on her good days. She understood she was leaving her house to me and her savings to charity."