N.H. Rev. Stat. Ann. § 490:7

Sessions of the court shall be held by at least 3 supreme court justices. A lesser number, or the clerk, if no justice attends, may adjourn the sessions from day to day until 3 justices attend. If one or more of the justices present is disqualified to sit in any case, one or more temporary justices may be assigned in accordance with RSA 490:3; provided that at least 3 justices, either full-time or temporarily appointed, must sit, participate, and decide.