The Catholic Church believes that marriages entered into by non-Catholics in their particular church, or wherever they may take place, are valid. In the eyes of the Church, even two atheists or agnostics who are married civilly before a judge or magistrate enter into a valid marriage. Catholics, however, are bound to observe a certain form of marriage ritual in order that their marriage be valid. Canon law—the law of the Church—requires that Catholics enter into marriage by free mutual consent that is witnessed in a church by an authorized bishop, priest, or deacon and at least two other witnesses. Marriages in which one or both parties are Catholic and which are not witnessed by an authorized bishop, priest, or deacon, or which do not receive proper permission to take place in another forum, are considered invalid in the eyes of the Church.
Simply put, If the couple has entered into a civil marriage and if either spouse is Baptized Catholic and they were not married in the Catholic Church, then they would need a Convalidation, to validate their marriage in the eyes of the Church.
Regardless of what happened in the past, the Catholic Church invites you to bring new meaning to your lives by embracing the vocation of marriage and dedicating your family’s mission to sharing God’s love.