On Tuesday, in a landmark ruling for estranged gay and lesbian parents, New York’s highest court expanded the definition of parent. The New York Court of Appeals reversed a 1991 ruling in Matter of Alison D. v. Virginia M., which held that nonbiological, nonadoptive parents have no legal standing to ask for custody and visitation rights of children. Before Alison D. was overturned, loving and stable caretakers who agreed to conceive and raise children as co-parents with ex-partners were left in the cold—treated as legal strangers—when their relationships ended.

The New York high court called Alison D.’s rigid standard of parentage “unworkable when applied to increasingly varied familial relationships.” The court emphasized that hard-and-fast rules on parentage “inflicted disproportionate hardship on the growing number of nontraditional families” across the state.

The Court of Appeals’ ruling came out of two combined cases, Matter of Brooke S.B. v. Elizabeth C.C. and Matter of Estrellita A. v. Jennifer D. The first dispute, between Brooke S.B. and Elizabeth C.C., concerned a woman who raised a boy with her former partner, the child’s biological mother. The nonbiological mother wanted joint custody and visitation rights but was turned away by the courts. Her motherhood was denied because she didn’t marry her partner or go through a formal adoption process.

The couple began their relationship in 2006 and announced a symbolic engagement four years before same-sex couples could marry in New York. They didn’t have the financial resources to travel out-of-state and secure formal recognition of their relationship. Even if they had traveled to marry in Massachusetts or obtained an out-of-state civil union, it was not clear at the time whether New York would recognize it.

Around that time, they decided to raise a child together and that Elizabeth would carry the child. After Elizabeth became pregnant, Brooke took part in the prenatal care and even cut their child’s umbilical cord when he was born in June 2009. The couple also gave the child Brooke’s last name. Brooke stayed at home with the child, who called her “Mama B,” for a year while Elizabeth returned to work.

In 2010, the couple split. Despite the breakup, the relationship remained amicable. Brooke maintained regular contact with their son until the exes’ relationship broke down and became unfriendly. Brooke filed a petition with state family court to restore her relationship with her son, but she was rebuffed by the court, even though the child’s court-appointed attorney said maintaining contact with Brooke was in the child’s best interest.

Because of Matter of Alison D. v. Virginia M., family court was forced to turn a blind eye to the harm inflicted on Brooke and Elizabeth’s son. The outdated, 25-year-old precedent blessed tearing Brooke out of her son’s life, no matter how fit a mother she was to him. An unnecessarily narrow understanding of family stood to allow a scorned ex-partner’s feelings to trump what was best for her child.

The second case involved a Long Island lesbian couple and was equally—if not more—troubling. The couple, Estrellita and Jennifer, moved in together in 2003. In 2007, they registered as domestic partners, and in 2008 Jennifer became pregnant by artificial insemination. As in Brooke and Elizabeth’s case, the nonbiological mother attended prenatal medical appointments and was present during labor and delivery. After raising the child together in their household for three years, the couple broke up in 2012. Jennifer then demanded that Estrellita pay child support. In an unsettling move, Jennifer also asked the courts to block visitation rights for her ex-partner on the grounds that she was not a legally recognized parent.

In effect, before the court’s Aug. 30 ruling, New York law could have been used to force a nonbiological, nonadoptive parent to pay child support but also ban them from asking the courts for custody or visitation rights—even when it was in the best interest of the child. That logical absurdity was not lost on New York judges. Indeed, the court emphasized that “the ultimate determination of whether [custody and visitation] rights should be granted rests in the sound discretion of the [family] court[s], which will determine the best interests of the child.”

The decision is limited, however. As Associate Judge Sheila Abdus-Salaam noted in the court’s opinion, the new rule’s reach is limited to cases in which “a partner shows by clear and convincing evidence that the parties agreed to conceive a child and to raise the child together.” A trickier issue that New York judges may have to render a decision on in the future is what to do in cases where there was no parenting agreement in place before conception.

The New York court recognized what some other state courts, most notoriously in Michigan and Alabama, have been slow to acknowledge: The traditional legal constructions of family require renewed scrutiny to ensure the law is meeting the needs of the modern family. Abdus-Salaam articulated this idea, highlighting the importance of Obergefell, when she wrote for the court, “By creating a disparity in the support and custody contexts, Alison D. has created an inconsistency in the rights and obligations attendant to parenthood. Moreover, Alison D.’s foundational premise of heterosexual parenting and nonrecognition of same-sex couples is unsustainable, particularly in light of the enactment of same-sex marriage in New York state, and the United States Supreme Court’s holding in Obergefell v. Hodges, which noted that the right to marry provides benefits not only for same-sex couples, but also the children being raised by those couples.”

The New York decision stands in stark contrast to the Michigan Supreme Court’s recent decision to not hear cases arising from similar facts where same-sex partners stand to lose contact with their children because they are nonbiological, nonadoptive parents. Worse than New York, however, Michigan denied same-sex couples the opportunity to marry or adopt prior to U.S. Supreme Court’s ruling in Obergefell v. Hodges in June 2015. The New York Court of Appeals decision is a victory for same-sex couples in New York, but it may have broader implications. It highlights that the status quo in outlier states like Michigan is not viable and, perhaps, ripe for federal court intervention.