https://www.nhs.uk/using-the-nhs/nhs-services/mental-health.../mental-health-act/
"But there are cases when a person can be detained, also known as
sectioned,
under the
Mental Health Act (1983) and treated without their agreement. ... People detained
under the
Mental Health Act need urgent treatment for a
mental health disorder and are
at risk of harm to themselves or others."