The New York State Court of Appeals ruled last week that a marriage between an uncle and a niece is legal.

The wife, 33-year-old Huyen Nguyen, faced deportation to Vietnam if the marriage to her half-uncle, 38-year-old Vu Truong was deemed illegal. The couple wed 14 years ago.

Truong and Nguyen's mother have different fathers, and are half-brother and sister. Because Truong and Nguyen share the same amount of genes as a pair of first cousins, the appeals court found no reason that they should not marry.

"First cousins are allowed to marry in New York, and I conclude that it was not the Legislature's purpose to avert the similar, relatively small genetic risk inherent in relationships like this one," Judge Robert Smith wrote in the unanimous decision. The "genetic risk in a half-uncle, half-niece relationship is half what it would be if the parties were related by the full blood", the judges added.

The court also considered the societal implications of the controversial marriage, writing that while "parent-child and brother-sister marriages ... are grounded in the almost universal horror with which such marriages are viewed ... there is no comparably strong objection to uncle-niece marriages".

Judge Victoria Graffeo and two other appeals judges noted that there are other considerations to make when weighing the legality of intra-familial marriages.

"Such relationships could implicate one of the purposes underlying incest laws, i.e., 'maintaining the stability of the family hierarchy by protecting young family members from exploitation by older family members in positions of authority, and by reducing competition and jealous friction among family members,' " Judge Graffeo wrote.

Reverend Jason McGuire, Executive Director of Christian conservative advocacy group New Yorkers for Constitutional Freedoms, questioned the wisdom of the ruling.

"If government's only interest in marriage is who loves each other, than what logical stopping point is there?" he asked.