Canonical impediments to ordination
*]Mental illness that prevents fulfillment of the duties of the priesthood.
*]Physical incapacity to perform the rites of the Church. A priest must have his hands to celebrate the sacraments. He must also be able to ingest the wheat host and the wine. (A complete gluten intolerance, for example, is an impediment).
*]Apostasy, heresy or schism. Previous rejection of the faith which was public and notorious is an impediment.
*]Attempted marriage. The attempt to marry despite an existing valid marriage or vow of chastity, or the marriage to a woman who had an existing valid marriage or vow of chastity forms an irregularity even after the death of the spouse.
*]Participation in an abortion or murder. Any prior act, statement, financial or moral support which contributed positively to a specific case of successful abortion or murder is an impediment. This could include driving a woman to the abortion clinic or paying for her abortion. Paying taxes to a state that funds abortions would generally not be considered a "positive" contribution to the abortion.
*]Attempted suicide, self mutilation, or mutilation of others. Any premeditated attempt at suicide disqualifies one as a candidate for ordination. The act of mutilation must be performed "graviter et dolose" in order for it to be an impediment (cutting off a hand or foot, castration, etc.)
*]Attempt to perform an act proper to the priesthood or episcopate. This applies to acts such as hearing confessions, etc. when one has not received the proper ordination to do so.
Simple impediments to ordination
*]Previous marriage. This applies to Latin Rite priests and bishops and Eastern Catholic bishops only. All previous marriages must be declared null, or the spouse must have died. In the case of a deceased spouse, most bishops require that the children be raised to adulthood before the man can undertake a vocation to the priesthood.
*]Political office or other positions that a priest is not permitted to occupy. This impediment disappears as soon as the candidate is no longer in office.
*]Recent baptism. The bishop must determine when a newly baptized person is sufficiently mature in his faith to undertake an ordained ministry in the Church.