N.H. Rev. Stat. Ann. § 502-A:21-a

A district court justice designated to be full-time under RSA 491-A:3, IV shall not be permitted to engage in the practice of law to any degree. Full-time justices shall receive the salary specified in RSA 491-A:1. Full-time justices chosen pursuant to this section shall, when requested by the supreme court, assist other district courts whenever a justice in such other court is disqualified, disabled, otherwise unable to sit, or in need of assistance.