Supreme Judicial Court Rules  Rules of Professional Conduct Rule 8.2: Judicial and legal officials

A lawyer shall not make a statement that the lawyer knows to be false or with reckless disregard as to its truth or falsity concerning the qualifications or integrity of a judge or a magistrate, or of a candidate for appointment to judicial or legal office. 

[1] Assessments by lawyers are relied on in evaluating the professional or personal fitness of persons being considered for appointment to judicial or legal offices. Expressing honest and candid opinions on such matters contributes to improving the administration of justice. Conversely, false statements by a lawyer can unfairly undermine public confidence in the administration of justice. A lawyer violates this Rule by impugning the integrity of a judge or magistrate either by making an intentionally false statement or by making a false statement when the lawyer has no reasonably objective basis for the statement.