A municipal court justice from Delaware County should be admonished for failing to disqualify himself from a case involving the daughter of his court clerk, the state Commission on Judicial Conduct said Thursday.

The commission ruled that Richard Gumo also failed to disclose that the clerk’s daughter was a key witness in a disorderly conduct case before the justice in 2011, that he allowed the clerk to perform clerical duties in the case involving the daughter and wrote a letter in a “fit of pique” to a county court judge who criticized Gumo’s handling of the matter.