PLEASE NOTE: Currently in the UK no mental health professional ever wears white coats and seldom wear uniforms of any kind unless they are nursing staff. CPN is the abbreviation for Community Psychiatric Nurse and they do not wear uniforms. Sectioning in other countries is the term that used to known as committed i.e. placed in hospital by decree from a medical team.
In the UK it takes a committee of medical staff trained in mental health to agree that you are too ill to be left to cope on your own and it is very common for a member of public not related to you to ensure that medical staff are not in breach of the law.
All people in the UK can appeal against being placed in hospital under the Mental Health Act.