dissenting:
The majority concludes that a child raised from the age of six months by a non-biological citizen father is not a citizen. Our case law, the governing federal and state statutes, and a proper application of the principles of cooperative federalism compel a different conclusion. Thus, I must respectfully dissent.
I
Juan Jose Martinez-Madera moved to the United States when he was six years old and has now lived here for over forty years. Martinez-Madera’s mother began a relationship with Jesus Gonzales, the man Martinez-Madera regards as his father, when Martinez-Madera was an infant. The IJ found it undisputed that “since [Martinez-Madera]’s age of 6 months Mr. Gonzales ... has held out that [Martinez-Madera] is to be his son and addresses him and adopted him into the family .... He has always held [Martinez-Madera] out to be a son and part of the family.” Martinez-Madera’s parents had six biological children together between 1954 and 1966. They married in 1960. Throughout his entire childhood, Martinez-Madera lived with his parents and siblings as a family unit. Gonzales provided for the entire family and publicly held himself out as Martinez-Madera’s father.
Now, Martinez-Madera claims derivative citizenship through Gonzales, a United States citizen. He cites our cases Scales v. INS, 232 F.3d 1159 (9th Cir.2000), and Solis-Espinoza v. Gonzales, 401 F.3d 1090 (9th Cir.2005), which establish that a person of foreign birth may derive citizenship through a non-biological U.S. citizen parent under 8 U.S.C. § 1401 (1964), so long as the person was not born “out of wedlock.” In both Scales and Solis-E spinoza, we looked to state law to determine whether the person was born in or out of wedlock.
Under California law, Martinez-Madera was clearly born in wedlock and thus derives United States citizenship from his father. The majority ignores the precedent set by Scales and Solis-E spinoza and in doing so contradicts established public policy and an express provision of the Immigration and Nationality Act (“INA”).
II
In Scales, we first had the opportunity to consider whether a person of foreign birth may derive U.S. citizenship through a non-biological parent. We examined the two relevant statutory provisions — 8 U.S.C. § 1401 and 8 U.S.C. § 1409 — and held that § 1401 does not “require a blood relationship between a person born outside the United States and his U.S. citizen parent.” Scales, 232 F.3d at 1161. We observed that § 1401 applies if the person claiming citizenship was born “in wedlock,” while § 1409 applies if the person was born “out of wedlock.” Thus, we proceeded to determine whether the petitioner was born in or out of wedlock. To make this determination, we looked to the relevant state law of the petitioner’s domicile. Indeed, we recognized that the INA provides that a child can be “legitimated under the law of the child’s residence or domicile.” Id. at 1163 (quoting 8 U.S.C. § 1101(c)(1) (1976)). We noted that the petitioner and his family had resided in the state of Washington since the petitioner was 11 years old and that Washington state law provided at the time that “[a] man is presumed to be the natural father of a child if: (a) He and the child’s natural mother are or have been married to each other and the child is born during the marriage.” Id. at 1163 & n.7 (quoting *944Wash. Rev.Code § 26.26.040(l)(a)). Applying this law, we concluded that the petitioner “is ‘legitimate’ by virtue of his parents being married at the time of his birth,” id. at 1164, and held “that Petitioner acquired citizenship at birth under § 1401,” id. at 1166.
In Solis-Espinoza, we confronted “a situation much like [that of Scales ], but with the genders of the parents reversed.” Solis-Espinoza, 401 F.3d at 1093. As in Scales, we looked to state law to determine whether the petitioner was born in or out of wedlock. We observed that “[t]he relevant state of domicile for Solis-Espinoza and his father was California,” id. at 1093, and thus applied a California state law in effect at the time. That law provided:
The father of an illegitimate child, by publicly acknowledging it as his own, receiving it as such, with the consent of his wife, if he is married, into his family, and otherwise treating it as if it were a legitimate child, thereby adopts it as such; and such child is thereupon deemed for all purposes legitimate from the time of its birth.
Cal. Civ.Code § 230 (1872). Applying that statute, we held: “Under the law of California at the relevant time ... Solis-Espinoza was ‘for all purposes legitimate’ from the time of his birth. Since he was not ‘born out of wedlock,’ under our decision in Scales ... he is entitled to be recognized as a citizen under § 1401.” Solis-Espinoza, 401 F.3d at 1094.
Section 230 applies to Martinez-Madera as well. Martinez-Madera’s non-biological father publicly acknowledged and treated Martinez-Madera as his own son since the age of six months. Section 230 therefore requires this Court to treat Martinez-Ma-dera as legitimate from the time of his birth. Thus, § 1409 does not apply and Martinez-Madera derives United States citizenship through his non-biological father pursuant to § 1401.
The majority attempts to distinguish Scales and Solis-Espinoza on the ground that Martinez-Madera was born “out of wedlock” because his parents were not married at the time of his birth.1 However, this difference does not vitiate the requirement of Scales and Solis-Espinoza that we look to state law to determine whether the petitioner is legitimately the child of the citizen parent.
Ill
In looking to state law, Scales and Solis-Espinoza adhered to an express provision of the INA. We have previously held:
Legitimacy is a legal concept, and the law determines whether and under what circumstances a child it has denominated illegitimate may become legitimate. The Immigration and Nationality Act provides that a child who is unmarried and under twenty-one years of age can be legitimated under the law of the child’s residence or domicile, or under the law of the father’s residence or domicile, whether in or outside the United States, if such legitimation takes place before the child reaches the age of eighteen years and the child is in the legal custody of the legitimating parent or parents at the time of such legitimation.
Burgess v. Meese, 802 F.2d 338, 340 (9th Cir.1986) (emphasis added) (citing 8 U.S.C. § 1101(b)(1)(C) (1983)); see also Scales, 232 F.3d at 1163 (quoting an earlier version of the same statute, 8 U.S.C. § 1101(c)(1) (1976), containing identical language).
*945Congress has expressly provided that a child who is considered “legitimated” under applicable state law is also to be considered “legitimated” for the purposes of immigration law. The majority ignores this express provision.
IV
Denying Martinez-Madera’s derivative citizenship claim also contravenes the public policy considerations we have traditionally respected in such cases.
First, as we observed in Solis-E spinoza: “Public policy supports recognition and maintenance of a family unit. The INA was intended to keep families together. It should be construed in favor of family units and the acceptance of responsibility by family members.” Solis-Espinoza, 401 F.3d at 1094. See also H.R. Rep. 85-1199, pt. 2, reprinted in 1957 U.S.C.C.A.N. 2016, 2021 (the INA “implements the underlying intentions of our immigration laws regarding the preservation of the family unit.”). Martinez-Madera lived with his parents and siblings as a family unit throughout his entire childhood and has resided in the United States for over forty years. To deny him derivative citizenship and deport him to Mexico is unjust, illogical, and does nothing to further U.S. immigration policy.
Second, the majority’s interpretation violates the principles of cooperative federalism. “Family relations are a traditional area of state concern.” Moore v. Sims, 442 U.S. 415, 435, 99 S.Ct. 2371, 60 L.Ed.2d 994 (1979); see also H.C. ex rel. Gordon v. Koppel, 203 F.3d 610, 613 (9th Cir.2000) (noting the importance of the state interest in family relations). Federal courts have no general jurisdiction over domestic relations, Ankenbrandt v. Richards, 504 U.S. 689, 697-701, 112 S.Ct. 2206, 119 L.Ed.2d 468 (1992), while “state courts have a special expertise and experience” in family relations, H.C., 203 F.3d at 613 (citing Hisquierdo v. Hisquierdo, 439 U.S. 572, 581, 99 S.Ct. 802, 59 L.Ed.2d 1 (1979)).
The best method of advancing these two policy objectives is to hold — consistent with the INA, Solis-Espinoza, and Scales — that state law governs determinations of legitimacy.
V
For all of these reasons, I would hold that courts should look to state law to determine whether a person may properly be considered “legitimate” or “born in wedlock” for the purposes of § 1409. Applying state law, I would hold that Martinez-Madera is “for all purposes legitimate” under Cal. Civ.Code § 2302 and is entitled to derivative citizenship under § 1401.
Because the majority has concluded otherwise, I must respectfully dissent.
. The majority cites a Fifth Circuit case in support of its conclusion. See Marquez-Marquez v. Gonzales, 455 F.3d 548 (5th Cir.2006). Aside from being non-binding on this Court, Marquez-Marquez does not explicitly evaluate whether Marquez-Marquez was bom into wedlock under the relevant state law.
. The majority additionally argues that even if California law should determine whether Martinez-Madera was born out of wedlock, he has not met the requirements of Cal. Civ. Code § 230 because that statute is applicable only to biological fathers. This argument relies on dicta from an 1892 California Supreme Court case. Although we normally follow a state supreme court's interpretation of a state statute, California caselaw simply does not answer the question of whether Cal. Civ.Code § 230 permits a step-father to legitimize his wife’s biological child. Absent clear direction from the California Supreme Court, which we do not have here, there is no compelling reason to interpret the California statute in the manner suggested by the majority.