Unlike states such as Georgia, Alabama, Idaho, Iowa and Kansas, California doesn’t recognize common-law marriage; a couple who are simply cohabiting aren't considered married in California, regardless of the number of years spent living together. This domestic partnership isn't recognized as lawful by the state, as the couple has no legal document to support their union — instead, it relies on a mutual understanding that entails treating each other as spouses. Both parties must mutually consent to the cohabitation and be of legal age, which is 18 in California.

Prior to 1976, California didn't recognize any rights pertaining to cohabiting couples. All the duties between the couple were considered self-imposed, and the relationship was inconsequential in terms of any legal dispute that arose after termination of the relationship. However, this changed in 1976 when California started recognizing any oral or written agreement signed by the couple while cohabiting. Although there was no specific law passed to enact the rights of cohabiting couples in California, the courts took into consideration the Marvin rationale and arguments that outlined the fair sharing of property upon termination of a relationship. Couples are now encouraged to sign a cohabitation agreement spelling out the obligations and rights of each partner and also defining the liability and property rights. The rights in this agreement, mostly pertaining to property and financial matters, are enforceable under the law. Oral agreements may be difficult to prove, so it is advisable for couples to consult a lawyer before entering into an agreement.

California family law doesn't provide automatic property rights and doesn’t recognize community property rights for unmarried cohabitants unless they have signed a cohabitation agreement. Cohabiting is irrelevant to property rights unless there's an existing agreement between the couple on division of property. The amount or share awarded to each partner is as stipulated in the contract and isn't affected by the length of time the couple has lived together.

Palimony is a popular but not legal term coined from the terms pal and alimony, which became popular in 1976 when Michele Marvin unsuccessfully filed suit against actor Lee Marvin, who she had cohabited with. Palimony describes division of property and financial assets after the end of cohabiting relationships. The law doesn't guarantee palimony unless there is a clear oral or written agreement between the partners stipulating the amount of support and financial sharing by the couple -- unlike in spousal support or alimony, which is supported by the law. Palimony cases are heard in a civil court, rather than in a family court that handles divorces, since they involve contract matters.