N.Y. Mental Hyg. Law § 9.55
A qualified psychiatrist shall have the power to direct the removal of any person, whose treatment for a mental illness he is either supervising or providing in a facility licensed or operated by the office of mental health which does not have an inpatient psychiatric service, to a hospital approved by the commissioner pursuant to subdivision (a) of section 9.39 of this article, if he determines upon examination of such person that such person appears to have a mental illness for which immediate observation, care and treatment in a hospital is appropriate and which is likely to result in serious harm to himself or others, as defined in section 9.39 of this article. Upon the request of such qualified psychiatrist, peace officers, when acting pursuant to their special duties, or police officers, who are members of an authorized police department or force or of a sheriff's department shall take into custody and transport any such person. Upon the request of a qualified psychiatrist an ambulance service, as defined by subdivision two of section three thousand one of the public health law, is authorized to transport any such person. Such person may then be admitted in accordance with the provisions of section 9.39 of this article.
N.Y. Mental Hyg. Law § 9.55