"Throughout most of history, the rights and obligations of marriage were informal, enforced by family or clan members. With the introduction of the Justinian Code in the 6th century, laws were established to regulate marriage. Nevertheless, for most couples in Europe, marriage continued as an informal arrangement. However, in 1563, the Council of Trent required that all valid Catholic marriages had to be celebrated in a Catholic church by a priest and before two witnesses. The Reformation effectively introduced civil marriage, regulated by the civil authorities, although it did not preclude marriage being solemnized in a reliious ceremony."
"Marriage." The Encyclopedia of Libertarianism. 2008. SAGE Publications.