Appendix 1 - Assessing the capacity of a child or young person
1. For any investigations or treatments you propose, you must decide whether a child or young person is able to understand what is involved, why you need to carry out the investigation or treatment, and what the possible consequences are. They must also understand the consequences of not having the investigation or treatment. They can consent to the investigation or treatment only if they are able to understand, retain, use and weigh up this information, and explain their decision to others. This means you must make sure that a child or young person has received all the relevant information and that it has been thoroughly discussed with them before deciding whether or not they have the capacity to consent to the investigation or treatment.
2. The capacity to consent depends more on a child’s or young person’s ability to understand and weigh up the options than on their age. When assessing their capacity to consent, you should bear both of the following points in mind.
a. You can presume that a young person has the capacity to consent at the age of 16 years.
b. A person younger than 16 years may have the capacity to consent, depending on their maturity and ability to understand what is involved.35
3. It is important that you assess each child’s or young person’s maturity and understanding, and consider the complexity and importance of the decision to be made. You should remember that a child or young person who has the capacity to consent to straightforward, relatively risk-free treatment may not necessarily have the capacity to consent to complex treatment involving high risks or serious consequences. A child’s or young person’s capacity to consent can also be affected by their physical and emotional development and by changes in their health and treatment.
See Family Law Reform Act 1969, Age of Majority Act (Northern Ireland) 1969, Age of Legal Capacity (Scotland) Act 1991, Adults with Incapacity (Scotland) Act 2000, Mental Capacity Act 2005, Gillick v West Norfolk and Wisbech AHA  UKHL 7