IV. The negative qualifications of a bishop determined.
In cities whose governors have died let this form be observed in filling up their place: he, who is to be ordained, even though his good life be not attested, shall be not a layman, not a neophyte, nor yet the husband of a second wife, or one who, though he has or has had but one, married a widow. For the choosing of priests is of such surpassing importance that things which in other members of the Church are not blame-worthy, are yet held unlawful in them.
Source: Letters (New Advent)