N.H. Rev. Stat. Ann. § 172:8-a

No reports or records or the information contained therein on any client of the program or a certified alcohol or drug abuse treatment facility or any client referred by the commissioner shall be discoverable by the state in any criminal prosecution. No such reports or records shall be used for other than rehabilitation, research, statistical or medical purpose, except upon the written consent of the person examined or treated. Confidentiality shall not be construed in such manner as to prevent recommendation by the commissioner to a referring court, nor shall it deny release of information through court order pursuant to appropriate federal regulations.