N.H. Rev. Stat. Ann. § 171-B:16

No person who is admitted to a receiving facility or to the secure psychiatric unit pursuant to this chapter shall be discharged, either absolutely or conditionally, prior to the expiration of the order of commitment without prior approval of the chief administrator of the state developmental services system when the person is committed to a receiving facility, or the commissioner of the department of corrections, when the person is committed to the secure psychiatric unit. No person who is transferred to the secure psychiatric unit pursuant to RSA 171-B:15 shall be discharged or transferred from the unit prior to the expiration of the order of commitment without prior approval of the commissioner of the department of corrections.