Where two females are legally married and have a child that one of them carries to birth, what happens to the non-birth parent's rights upon a separation or divorce? The answer is that basically the same outcomes and principles will apply in a same sex divorce that apply to a heterosexual couple in a similar situation. That principle was enunciated by the United States Supreme Court in 2014 and applies in all jurisdictions, including New York.
In the real-life case, the biological mother argued to a state appellate court that the rules that give a presumption of parental rights only apply to a man. She has argued that they do not apply in this case to the noncustodial female spouse who is also the non-biological parent. The state appellate court rejected that argument, ruling that it does not comport with U.S. Supreme Court precedent.
The two females were married legally in 2008 in California. The birth mother was artificially inseminated in 2010, and they moved to Arizona before the baby was born. The couple entered in a joint parenting agreement and executed identically reciprocal wills. They inserted a provision stating that they were to be equal parents to the child.
The non-birth mother stayed home and took care of the baby boy, while the birth mother went out and worked as a physician. Within about two years, the non-biological mother left the marital residence and took the boy with her, cutting off all ties with the biological mother. She later filed a divorce and argued that she was entitled to her rights as a parent.
The biological mother countered that she is the only person with parental rights by being the sole genetically-related individual. The appellate court rejected that argument, citing to the above-mentioned Supreme Court precedent. The appellate court ruled that the couple is guaranteed a civil marriage on the same terms and conditions as the heterosexual couple, and the same sex divorce would follow the same principles. Although the case was litigated in another state, it would likely be decided similarly under similar facts in a New York court.
Source: azdailysun.com, "Appeals court rules on same sex parental rights", Howard Fischer, Oct. 11, 2016