The highest court in New York State has redefined how the state legally defines parenthood ruling that non-biological and non-adoptive parents can seek visitation and custody of a child if a couple breaks up. Previously, the state only recognised parents who were biologically related or related through adoption.

According to The Wall Street Journal, the decision on on Tuesday (30 August) reverses a 25-year-old ruling that banned same-sex couples from seeking the court's help in custody cases. The New York Court of Appeals stated that families headed by same-sex couples need protection.

Judge Sheila Abdus-Salaam, who was backed by four other judges, ruled that the court was wrong in its 1991 decision which established a "needlessly narrow" rule limiting the definition of parenthood to biology and adoption.

The case, involving a lesbian couple and referred to as Alison D v. Virginia M, led the courts to "permanently sever strongly formed bonds between children and adults with whom they have parental relationships."

A person could seek visitation and custody rights if it is proven "by clear and convincing evidence that the parties agreed to conceive a child and to raise the child together." The Journal reported that the court acknowledged that some people who come into a child's life after birth could also deserve custody but did not set a rule for those situations.

The court's decision was welcomed by gay-rights advocates. "Finally, New York is bringing its law in line with the reality of thousands of children who need protection for their relationships," Susan Sommer, an attorney at gay-rights organisation Lambda Legal who was involved in the case, told the Journal. "No longer is there some harsh, absolute bar."

However, opponents to the ruling say that the new parental rules could allow abusive partners or someone claiming ties to a child to bring biological parents to court for false custody challenges.

According to The Associated Press, the decision resolves appeals of two New York state custody challenges involving former unmarried same-sex couples where the biological mothers kept custody of the children and their ex-partners sought legal right to see them. A Massachusetts court is also expected to make a decision soon in a case challenging how the Bay State recognises parents.

The Associated Press noted that the ruling will also affect heterosexual, unmarried couples.