RALEIGH — A state senator’s personal life reached the N.C. Supreme Court on Wednesday as justices listened to arguments whether her adoption of her former domestic partner’s biological son was legal.

The outcome of the custody case involving N.C. Sen. Julia Boseman of Wilmington and ex-partner Melissa Jarrell could decide whether state law allows a certain kind of adoption by some same-sex couples in North Carolina.

In the so-called “second parent” adoption, which attorneys say are being granted in a few counties, an N.C. District Court judge granted Boseman’s request to adopt Jarrell’s son in 2005. The Durham County judge also waived a requirement that Jarrell relinquish her parental rights to Jacob, who will turn 8 years old next month.

The couple broke up the next year. In the custody fight, both women received joint custody. But Jarrell argued the adoption should be voided because “second parent” adoptions don’t exist in North Carolina law.

A trial court and the N.C. Court of Appeals panel upheld Boseman’s adoption, but Jarrell attorney Leslie Fritscher told the justices an “activist adoption court pushed along by activist attorneys” exceeded the reach of state law by granting the adoption and allowing Jarrell to keep her parental rights.

State law lays out four ways adoption can occur, but not this method, according to Fritscher.

“Courts may not substitute their own preferences for those of elected legislative representatives,” Fritscher said.

“Here the adoption court created its own adoption procedure, cobbling together various statutes to make a new kind of adoption that’s not provided for in the adoption statutes.”

Justice Patricia Timmons-Goodson pointed out that Jarrell consented to Boseman’s adoption and now wants it voided: “Should we be concerned about her then coming and complaining about this?” Fritscher said it doesn’t change that the lower court judge skirted adoption rules.

Boseman attorney Jim Lea called the adoption a “direct placement” adoption identified in the law in which Jacob was placed with a prospective adoptive parent. The Legislature hasn’t expressly barred such cases where the adoptive parents are unmarried partners and one is a biological parent, he said.

Jarrell missed all deadlines to challenge the adoption and expressly sought it in 2005. Now she’s changed her mind, and voiding it now would harm the well being of their son and his two-parent family, Lea told the court.

“Anything that’s in dispute in the adoption process is supposed to be construed in favor of the child,” Lea said. “That’s what we can’t missed here, that it’s all about Jacob.”

Associate Justice Paul Newby postulated that under Lea’s reasoning three parents could adopt a child under Lea’s reasoning. Lea disagreed, but Newby said the adoption raised questions whether alternative adoptions are allowed.

“Isn’t that just evidence this is a policy argument best for the Legislature?” he asked Lea.

A final ruling by the seven justices is likely to be months away.

Jarrell and Boseman both listened to the arguments in person. Each declined comment after the hour-long hearing.

At least 27 states permit second-parent adoptions through state law or based on evidence in local courts, according to the Human Rights Campaign. Judges in Orange and Durham counties have regularly decreed such adoptions in recent years, so family law lawyers are looking for clarity.

“This really is going to be the next wave of family law focus,” said Michelle Connell, a Winston-Salem family law specialist who isn’t involved in the case. “These situations are not going away because there are (local courts) that are doing this.”

Groups representing law professors, female attorneys and the American Civil Liberties Union filed briefs urging the court to uphold the adoption. Several Christian groups wrote asking the court to reverse the lower court decision because Boseman is neither an adoptive parent nor a third party who has a right to custody.

Jarrell and Boseman were living together when the child was born in 2002. Jarrell conceived through artificial insemination, and Boseman has been actively involved in Jacob’s life ever since, according to court documents.

Boseman, a Democrat, became the state’s first openly gay legislator when she was elected to the Legislature in 2004. She didn’t run for re-election in November and will complete her term at year’s end.