Section 15.13. Voluntary admissions

(a) The director of any school may receive as a voluntary resident any
  person  suitable  for  care and treatment, who voluntarily makes written
  application therefor. If such person be under eighteen years of age  the
  application shall be made by the parent or legal guardian or next-of-kin
  of such person.
    (b)    If  such  voluntary  resident  gives  notice  in writing to the
  director of the resident's desire to  leave  the  school,  the  director
  shall  promptly  release  the resident; provided, however, that if there
  are reasonable grounds for belief that the resident may be  in  need  of
  involuntary care and treatment, the director may retain the resident for
  a  period  not  to exceed seventy-two hours from receipt of such notice.
  Before the expiration of such  seventy-two  hour  period,  the  director
  shall  either  release the resident or apply to a court of record in the
  county where  the  school  is  located  for  an  order  authorizing  the
  involuntary  retention of such resident. The application and proceedings
  in connection therewith shall  be  in  the  manner  prescribed  in  this
  article  for  a  court  authorization to retain an involuntary resident,
  except that notice of such application shall be served forthwith and, if
  a hearing be demanded, the date for hearing to be  fixed  by  the  court
  shall  be  at a time not later than three days from the date such notice
  has been received by the court.  If it be determined by the  court  that
  the  resident  is  mentally  retarded    and  in  need  of retention for
  involuntary care and treatment in the school, the court shall  forthwith
  issue  an  order authorizing the retention of such resident for care and
  treatment in the school, or, if requested by the resident, his guardian,
  or committee,  such  other  non-public  school  as  may  be  within  the
  financial  means  of the resident, for a period not exceeding sixty days
  from the date of such order. Further applications for retention  of  the
  resident  for  periods  not  exceeding one year, and successive two year
  periods thereafter, respectively, may thereafter be made  in  accordance
  with the provisions of this article.
    In  the  case  of  a resident under eighteen years of age, such notice
  requesting release of the resident may be given by the resident, by  the
  person  who  made application for his admission, by a person of equal or
  closer relationship to the resident, or  by  the  mental  hygiene  legal
  service.  If  such notice be given by any other person, the director may
  in his discretion refuse to discharge the resident and, in the event  of
  such  refusal, such other person or the mental hygiene legal service may
  apply to the supreme court or to a county court for the release  of  the
  resident.