Barring a woman from seeking custody of her former same-sex partner’s biological child could have far-ranging legal implications that could threaten family relationships, particularly in cases where children are conceived using assisted reproductive technologies, an attorney told the Pennsylvania Supreme Court on Tuesday.

Attorney Tiffany Palmer of Jerner & Palmer, whose client is seeking to assert custody of her ex-partner’s biological child, urged the justices to reject the state Superior Court’s holding that a same-sex partner who had not adopted a child could not be considered a parent. That legal error, she argued, has thrown the custody rights of all non-biological parents into question.