§1. A judge is not to undertake the adjudication of a case in which the judge is involved by reason of consanguinity or affinity in any degree of the direct line and up to the fourth degree of the collateral line or by reason of trusteeship, guardianship, close acquaintance, great animosity, the making of a profit, or the avoidance of a loss.
§2. In these circumstances the promoter of justice, the defender of the bond, the assessor, and the auditor must abstain from their office.
Source: Code of Canon Law (Vatican.va)