A California appellate court held last week that partners in domestic partnerships that are not legal have the same rights as couples in bigamous relationships who believe they are married.

According to a report in the Los Angeles Daily Journal, Darrin Ellis, a 35-year-old Newport Beach hairdresser, sought to dissolve his partnership with David James Arriaga, a 44-year-old manufacturer of auto parts.

The pair signed and notarized a domestic partnership agreement in 2003, but they never finalized it by filing it with the secretary of state. Over the course of their relationship, they had amassed assets.

In 2006, Ellis filed a petition in Orange County Superior Court to dissolve the relationship. Ellis indicated to the court that he and Arriaga had complied with the requirements of the Domestic Partner Act. But Arriaga asked a court to dismiss the action because he (Arriaga) had never mailed the partnership form to the secretary of state.

Arriaga argued that absent a lawful domestic partnership the court had to treat the two men as “roommates” or as “nonmarital partners,” which means neither would have any interest in the other’s income.

Ellis contended that, even if the domestic partnership was not entirely legal, Arriaga was akin to his “putative spouse.” This means he had a good faith belief in the legality of his domestic partnership, and a court should treat him as a lawful spouse or, in this case, a lawful domestic partner.

Thus, Ellis contended, the court should treat him exactly the same as a spouse who discovers his or her marriage is invalid. Such a situation usually occurs when one spouse’s former legal marriage is not properly dissolved, thus nullifying the second marriage because one of the spouses is still married to someone else. It’s called “bigamy,” and it’s quite common, given that most states require a waiting period before a marriage is formally terminated.

Rather than punish the second spouse for the still-married spouse’s misdeed, the courts have created an equitable doctrine called the “putative spouse.”

The putative spouse is someone who has a “good faith” and a “reasonable belief” that the marriage is valid. Thus, the putative spouse can claim a community share of the property accumulated, and is entitled to support rights, should she or he have a rightful claim.

While the putative spouse doctrine has been around for decades, it has never been applied outside of the heterosexual marriage model. In fact, a previous California appellate court had ruled that the doctrine does not apply to “domestic partners,” because the state law has specific requirements.

But the more recent decision distinguished the previous ruling, finding that the couple in that case had known they were not registered partners. In this case, however, Ellis thought he was in a lawful partnership.

Applying the doctrine to any partnership can have significant economic consequences.

For example, under California’s Domestic Partner Act, couples can elect to consider their accumulated property as “community property” or “separate property.”

There are also support rights that attach.

The court last week ruled that the Legislature desired same-sex couples to have the very same rights as heterosexual couples. That being so, it only followed to apply the putative spouse doctrine to a domestic partner.

The decision could have a profound impact for the 49,000 couples who have filed for domestic partnership status in California. And, of course, it has a direct impact on those who “think” they are registered partners, but because of a legal impediment are not “lawful” partners under California law.