An impediment to Christian marriage. Two forms of this impediment are commonly recognized by ecclesiastical law: invalid marriage and public or notorious concubinage. An invalid marriage here means an apparent contract between man and woman which has at least the appearance of marriage but is in fact invalid. However, a so-called civil marriage, where a Catholic is concerned, is held not to have even the appearance of marriage, and therefore does not create this impediment, in the absence of cohabitation. Concubinage means a cohabitation between a man and a woman, established on a more or less durable basis without marriage. This impediment invalidates marriage in the direct line only, to the second degree. Thus a man cannot validly marry the mother or grandmother, nor the daughter or granddaughter, of a woman who was his mistress or pseudo-wife. Dispensations are given, provided there is no danger that the second partner may be the man's daughter, which is possible if he had relations with the mother before her daughter's birth.