The psychiatrist encounters canonical law either as an expert or in the position of a doctor to whom the patient or his relative turns with advice. His role in the first case is to confirm or rule out the presence of a mental disorder at the time of the churching of marriage. The sacrament of marriage is designed to perfect the love of the spouses and to strengthen their inseparable unity. By this grace, „in married life, as well as in the adoption and upbringing of children, they help one another to holiness" (CCCH 1641). The validity of the marriage is disqualified for both nonmedical and medical reasons. The marriage did not arise (even though both parties do not know about it), when at the time of its potential formation there were obstacles - defects of its fulfilment. If the ecclesiastical court declares the nullity of the marriage (nullitas matrimonii), it means that the marriage never existed (that is, there is no divorce, because the bonds of wedlock never arose). From a psychiatric point of view, this is the case when, due to the presence of a mental disorder at the time of the churching of the marriage, at least one of the following obstacles can be proved: 1. lack of use of reason, 2. serious lack of distinctive judgment, 3. inability to take on the essential obligations of marriage for reasons of a mental nature. The title of the dispute is determined by the ecclesiastical tribunal. The Canon law does not allow the site to be compelled to be personally examined, nor to use information from the medical records of the invited site if it does not agree. All sites testify under oath. If the expert finds the presence of a mental disorder (in this case active alcohol dependence) at the time of the churching of the marriage, the conclusion of his opinion may serve as evidence in court – a basis for declaring the marriage invalid for medical reasons.

Key words: canon law – alcohol dependence – sacrament of marriage – nullity of marriage – defects in marital consent