A justice shall not sit in any case in which he has been concerned as party or attorney or in any appeal in which he has acted as judge in the court below, or act as attorney or be of counsel for either party or give advice in any matter pending or which may come before the court for adjudication.
N.H. Rev. Stat. Ann. § 492:1
Counsel, Etc
Source
Official source: New Hampshire General Court. Reproduced from public-domain New Hampshire statutes; confirm against the official source for the current text. Not legal advice.