Remember that three factors are to be kept in mind regarding a valid sacrament of marriage. The law states that marriage is brought about (c. 1057) through: (1) the consent of the parties (the bride and groom), (2) legitimately manifested, (3) by those qualified according to the law (again, the bride and the groom).
Once the bride and groom exchange their vows, the marriage (c. 1055) that takes place is legally presumed (c. 1060) to be a valid sacrament. Yet if enough information is brought forward to indicate otherwise, the presumption of validity will yield to a declaration of nullity. For instance if one or both of the persons was unqualified by law to place consent - then marriage was NOT brought about.
The qualifications of the parties
A great deal of pastoral care and preparation is required before a couple celebrates their marriage (cc. 1063-1072). Part of this preparation is concerned with the ministers' legal qualifications to administer marriage. In some particular instances individuals are impeded from doing so.
Certain laws render a person incapable of contracting marriage validly (cc. 1073-1082). These laws are called diriment impediments. Many (though not all) of these impediments can be dispensed prior to the marriage. Once the requirement is dispensed, the person is then rendered capable of marriage. There are twelve specific diriment impediments listed in law (cc. 1083-1094).
A required age
One of the twelve impediments requires the minister must be a specific age. You may be amazed to hear that it is sixteen for a boy and fourteen for a girl! Before you fall off your chair remember that the law of the church is world-wide. As hard as it is to believe, these ages are acceptable in some cultures.
If someone below the stated age attempts marriage, they do so invalidly. Let's suppose a young man claims to be eighteen when in fact he is five days short of his sixteenth birthday. He marries an eighteen year old woman. The wedding is lovely and everyone presumes a marriage has been brought about.
A year later the couple divorces. The woman wishes to remarry, but is unable to do so because her prior bond is presumed to be valid. If she can prove in church court that the groom was not of legal age at the time of consent, the marriage would be declared null. The presumption that this was a valid marriage yields to a declaration of nullity. The groom was in fact incapable by law of placing consent.
Sister Martha B. Badd ...
A person in sacred orders or religious vows who attempts marriage also does so invalidly. Suppose Sr. Martha B. Badd of Boston travels around the country a great deal in her apostolate. She meets, and over time, falls in love with a man from Denver. She neglects to tell him she is a religious woman. She also neglects to mention this to the priest who is going to officiate at their wedding in Denver. The priest (like the groom) is so taken by Sr. Martha's personality that he doesn't follow through on the necessary paperwork and the wedding occurs. Everyone assumes they have just witnessed a marriage.
A month later Sr. Martha can no longer live with her deception and confesses the truth. The marriage would be declared null because she was incapable by law from placing consent.
Protecting the common good
Marriage is more than a "private" act between two parties. It affects the faith community at large. These impediments exist to protect both the individuals involved and the wider community. Aside from those mentioned above other situations prohibit an individual from placing a valid act of consent on a wedding day. A person who commits the following two specific crimes in order to marry, does so invalidly: abducting the intended spouse; murdering the husband or wife of the intended spouse.
A valid, prior bond of marriage renders a person incapable of marriage. It has unfortunately happened that a person has lied about a previous marriage. Though pre-marital investigations attempt to address this type of deception, they are not always successful.
As an aside, you may read in the parish bulletin that two individuals are soon to be married. These are called the banns of marriage. This is more than a social announcement. It is a legal observance to ascertain the freedom of both parties to marry. Remember, many laws exist simply in response to abuses. Sadly, people are not always honest about past marriages.
Pre-existing relationships between the parties may also render an individual incapable of marriage. For example, direct blood relationships - King Oedipus could not validly marry his mother! Some relationships through adoption and marriage ("in-laws") also may render one incapable of valid consent.
A Catholic who wishes to marry an unbaptized person must first receive a dispensation from disparity of cult. As the Catechism of the Catholic Church states this dispensation: "... presupposes that both parties know and do not exclude the essential ends and properties of marriage and the obligations assumed by the Catholic party concerning the baptism and education of the children in the Catholic Church (CCC, 1635)."
The legal presumption of validity will yield
The law presumes that the premarital investigations have determined the ministers are legally capable of marriage. However, if after a marriage, a couple divorces and they can prove that a diriment impediment existed at the moment of consent, the marriage is declared null.
More often than not the existence of a diriment impediment is discovered during an tribunal investigation of defective consent. If the impediment is proven, the formal processes regarding consent cease and the marriage is declared null by reason of the undispensed diriment impediment.
These cases are extremely rare - perhaps one or two a year. This fact bespeaks the great care priests, deacons and pastoral associates give to premarital preparation for the thousands of marriages that take place each year throughout the Archdiocese.
Next, is every marriage indissoluble? ...