Legal Definitions - mental capacity

Mental capacity refers to a person's ability to make their own decisions at a particular time, regarding a specific matter. This involves understanding the information relevant to the decision, appreciating the potential consequences of making or not making that decision, retaining the information for long enough to make a choice, and being able to communicate that choice.

It's important to note that mental capacity is not a general state; a person might have the capacity to make some decisions but not others, or their capacity might fluctuate over time. The assessment of mental capacity is always specific to the decision being made.

Here are some examples illustrating mental capacity:

• Medical Treatment Consent: An adult patient is presented with a complex medical procedure by their doctor. To have mental capacity for this decision, the patient must be able to understand the nature of the procedure, its potential benefits, risks, and any alternative treatments. They must also be able to weigh this information and communicate their choice to either accept or refuse the treatment. If they cannot grasp these key aspects, they might be deemed to lack capacity for that specific medical decision.

• Executing a Will: An individual wishes to create or update their last will and testament. For the will to be legally valid, the person must possess mental capacity at the time they sign it. This means they must understand that they are making a will, know the extent of their property, recognize the people who would naturally be beneficiaries (even if they choose not to include them), and understand the effect of their decisions on the distribution of their assets. If, for instance, they are suffering from a delusion that significantly impacts their understanding of their family or assets, their capacity to make a valid will might be questioned.

• Entering into a Contract: A person decides to sell a significant asset, such as a piece of land, and needs to sign a sales agreement. To have mental capacity for this transaction, they must be able to understand the terms and conditions of the contract, the price, their obligations, and the legal implications of signing the document. If they are unable to comprehend the basic elements of the agreement or the financial consequences, perhaps due to a severe cognitive impairment, they might be considered to lack the capacity to enter into that specific contract.