N.H. Rev. Stat. § 135-C:53
Any person who has been involuntarily admitted to a receiving facility may file at the probate court of the county in which he was originally admitted, or where he resides, a petition setting forth his name, the underlying circumstances and date of the prior order of the court ordering his involuntary admission, a request for discharge from care and custody or admission to a receiving facility, and the reasons for such request. The petition shall be accompanied by the certificate of a psychiatrist stating that the patient is no longer in need of involuntary admission and setting forth the facts upon which such an opinion is based. Upon receipt of the petition and the certificate, the court shall conduct a hearing pursuant to RSA 135-C:34-54.
RSA 135-C:53
1986, 212:1, eff. Jan. 1, 1987.