In a decision some gay-rights lawyers are calling a landmark, a state appeals court has recognized for the first time that New York state’s family law “presumption of legitimacy”—which says that a child born during a marriage is presumed to be both spouses’ child—applies to a child born to a same-sex married couple.

An Appellate Division, First Department, panel ruled that Han Ming T., the married partner of Marco D., a gay man now living in New York, should have been given notice of a petition to have their child adopted by Marco D.’s new gay partner.