A common law marriage is established between a (heterosexual) couple who lives together and acts as a married couple without a formal ceremony or legal paperwork. It's as simple as that. Common law marriages entitles a couple to all the rights and privileges of "regular", church- (by which I mean religion-) and state-sponsored marriage, but because there is no formal legal document registering the relationship, common law marriage is somewhat less well-defined and more difficult to legally prove. As a result, the social status of common law marriage is subject to some ambiguity, which is probably why the distinction is still made (like in the media, for example). Some of the criteria most often used to determine common law marital status include:
- living together and presenting yourself as married to your community
- using the same last name
- filing joint income taxes
Contrary to urban legend/popular belief, there is no magic minimum time period for living together that automatically confers common law married status (seven years or ten years are often cited, but not actually meaningful). In the United States, common law marriages can only be formed in states with laws that recognize them, but other states are required to recognize the unions thus formed, even if they themselves do not have a common law marriage law. The 14 states that recognize common law marriage at the time of this writing are:
Alabama, Colorado, the District of Columbia, Georgia (if the union was formed before 1/1/97), Idaho (unions formed before 1/1/96), Iowa, Kansas, Montana, New Hampshire (for inheritance purposes only), Ohio (if created before 10/10/91), Oklahoma, Pennsylvania, Rhode Island, South Carolina, and Texas.
If you live in one of these states and are worried about your marital status, it might be a good idea to research the law. If you live in one of these states and are concerned about maintaining a strictly living-together relationship status, you and your partner might want to sign a statement agreeing that your relationship is NOT a common law marriage. Finally, because common law marriage is completely legally equivalent to "regular" marriage, it must be ended in a regular legal divorce (if any such proceedings can be considered "regular"... *shudder*).
Source: Toni Ihara, Ralph Warner, and Frederick Hertz. The Living Together Kit: A Legal Guide for Unmarried Couples. Berkeley, CA: Nolo Press, 1999 (ninth edition).