Because Christ insti­tuted this sacra­ment, he also gives a man and a woman their vocation to marriage. The covenant thus in­volves not only a man and a woman, but also Christ. In establishing marriage as a vocation in life, God gave it the characteristics that enable human love to achieve its perfec­tion and allow family life to be full and fruitful. Outside marriage, or without a proper realization of its nature, the right conditions for the fruitfulness of human love and for a suc­cessful family life do not exist.

The Catholic Church has the right to establish laws re­gard­ing the validity of marriages, since marriage for the baptized is both a covenant and a sacrament. And it is only the Ca­tholic Church that has jurisdic­tion over those mar­riages, with due regard for the competence of civil au­thority concerning the merely civil effects. No one other than the Church has the power or authority to change ecclesiastical laws.

Unity of marriage signifies that the covenant estab­lished is between one man and one woman: the husband cannot ma­rry another woman during the lifetime of his wife, nor can the wife marry another man during the lifetime of her husband. Polygamy-having more than one spouse at the same time-is contrary to the equal personal dignity of men and women, who in Matrimony give themselves with a love that is total and, therefore unique and exclusive.

Indissolubility refers to the fact that the bond of sacramental mar­riage cannot be broken except by the death of either the hus­band or the wife.

Matrimonial con­sent is an act of the will by which a man and a woman, in an ir­revocable covenant, mutually give and accept each other, declaring their willingness to wel­come children and to educate them. Consent must be a free act of the will of each of the con­tracting parties, without coercion or serious fear arising from external circumstances. To be free means:

• •To be acting without constraint.
• •To be unimpeded by natural or ecclesiastical law.  Only those capable of giving valid matrimonial con­sent can get married: Matrimony is created through the consent of the parties-consent legitimately manifested between persons who, accord­ing to law, are capable of giving that consent.
  

1.  The contracting parties must be capable, according to Church law, of giving matrimonial consent. Before Ma­tri­mony is celebrated, it must be evident that no impediment stands in the way of its valid and licit (lawful) celebration.
2.  The consent given by the parties must be deliber­ate, fully volun­tary, free, mutual, and pub­lic. Therefore, the fol­lowing are incapable of contracting marriage:

• •Persons who lack sufficient use of reason.
• •Persons who suffer from grave lack of discretion of judgment concerning essential matrimonial rights and duties that are to be mutually given and ac­cepted.
• •Persons who, because of serious psychic illness, can­not as­sume the essential obligations of Matrimony.

As a condition for marriage, the Church re­quires that a man has com­pleted his sixteenth year (one's sixteenth year is completed the day after one's sixteenth birthday) and that a woman has completed her fourteenth year of age (one's fourteenth year of age is completed the day after one's fourteenth birthday). These ages are the min­ima for validity. There may be civil laws, as well, reg­ulating the minimum age for each state and country, but failure to comply with these laws does not invalidate marriage in the eyes of the Church.

Marriage is permanent, because God established it so from the very beginning. The indis­solubility of marriage is for the good of husband and wife, their children, and human society as a whole. The civil government has no power to dissolve a valid marriage-even if the marriage is between non-Catholics.

The government can dis­solve only the civil aspects of marriage, such as ownership of property, custody of the children, etc. Even when civil divorce is allowed by the country's law, mar­riage, in God's eyes, still ex­ists.

• The Church does not have the power to dissolve a valid, sacra­mental marriage that has been consum­mated. She may declare a marriage null and void only upon investigation and on evidence that the marriage did not exist from the very beginning. The reasons could be one of the following:
  
  •Lack of fully voluntary and free consent.
  •Some deficiency in the form of the marriage celebra­tion.
  •The presence of an impediment that makes a marriage in­valid.