Updated

The Washington state Supreme Court on Thursday ruled that a woman who raised a child from birth to age 6 while in a relationship with the girl's biological mother can seek parental rights as a "de facto parent (search)," essentially creating a new class of parent in the state.

"Today we hold that our common law recognizes the status of de facto parents and places them in parity with biological and adoptive parents in our state," the court, led by Justice Bobbe J. Bridge, wrote in the 7-2 decision. "Neither the United States Supreme Court nor this court has ever held that 'family' or 'parents' are terms limited in their definition by a strict biological prerequisite."

Sue Ellen Carvin (search), who goes by "Mian," sued her former partner, Page Britain (search), in King County Superior Court in November 2002, alleging that Britain had unfairly cut off access to Britain's biological daughter, identified in court papers as L.B.

The two had been together for about six years when they decided to raise a child together. Britain was artificially inseminated and gave birth in 1995. For the next several years, Carvin stayed home to raise the girl, who called her "Mama" and Britain "Mommy."

But a year and a half ago, Britain and Carvin split. Britain married the sperm donor and subsequently barred Carvin from seeing L.B.

The high court's ruling affirms a May 2004 ruling by the state Court of Appeals, which had ruled Carvin could seek parental rights to L.B. The three-judge panel found that while Carvin did not have standing under the state's Uniform Parentage Act, she could seek status as a "de facto or psychological parent" by presenting evidence of a parent-child relationship.

The high court remanded the case to trial to determine whether Carvin is L.B.'s de facto parent.

"We strongly urge trial courts in this and similar cases to consider the interests of children in dependency, parentage, visitation, custody, and support proceedings," the court wrote, and "to act on their behalf and represent their interests would be appropriate and in the interests of justice."