One of the strongest presumptions in law is the presumption of legitimacy: the presumption that a child born to a marriage is the legitimate child of both parents.
Likewise there is a presumption that a child born to a woman though artificial insemination with the consent in writing of the woman and her husband, shall be deemed the legitimate birth child of the husband and his wife.
Recently a New York court had to consider whether the presumptions of legitimacy applied to married same sex parents.
The legally wed couple both signed the required consent form for artificial insemination, but failed to obtain the statutorily required acknowledgment. The birth mother attempted to use absence of the acknowledgment, in essence, failing to sign the consent before a notary, to deny other parent her parental rights.
Since New York’s Marriage Equality Act provides that no “common law” provisions relating to marriage “shall differ” because the married couple have the same sex, the Court ruled:
To impose the presumption of consent to AID for couples in a heterosexual marriage, but not for those in a same-sex one, when both are similarly situated, but for sexual orientation, would reverse the gender-neutral approach to New York’s families canonized in the MEA….
The pervasive and powerful common law presumptions that link both spouses in a marriage to a child born of the marriage - the presumption of legitimacy within a marriage and the presumption of a spouse's consent to artificial insemination - apply to this couple. This court holds that the non-biological spouse is a parent of this child under the common law of New York as much as the birth-mother
Prior to this decision, it was standard practice in New York for the non-biological parent to adopt the child to “establish” parental rights. Because same-sex marriage is not recognized throughout county, it may be necessary to continue practice; other states may refuse to recognize the parties’ marriage or New York’s presumption of legitimacy for child born to a same sex couple.