WESLEY, Circuit Judge:

I.

A.

Carlos Garcia was born in the Dominican Republic on December 24, 1978. His family immigrated to the United States in 1984, and shortly thereafter, he became a lawful permanent resident. When Garcia's family arrived in the United States, they resided on West 107th Street in Manhattan.

In 1988, while his family was vacationing in the Dominican Republic, his mother divorced his father in a Dominican court. The divorce decree purported to grant Garcia's mother "guarda personal" ("personal guardianship").1 Following the vacation, Garcia's family returned to Manhattan and his parents continued living together on West 107th Street. In 1989, the entire family moved to 201 West 109th Street, and in August 1994 (six years after the divorce), Garcia's mother finally moved into her own apartment.

On April 20, 1996, when Garcia was under the age of eighteen, his father naturalized. Garcia alleges that at the time, he resided with his father and that his father had "actual uncontested custody" of him.

B.

On January 27, 1998, the former Immigration and Naturalization Service ("INS") charged Garcia as removable under Immigration and Nationality Act ("INA") § 237(a)(2)(C) (conviction for a firearm offense). INS took Garcia into custody until an immigration judge ultimately cancelled his removal. See Garcia v. U.S. Dep't of Homeland Sec., 657 F.Supp.2d 403, 405 (W.D.N.Y.2009). Garcia, however, soon found himself back on the wrong side of the law.

As a result of several convictions in 2001 and 2002, the Government served Garcia with a Notice to Appear and ultimately ordered him removed to the Dominican Republic. Garcia applied for derivative citizenship based on his father's 1996 naturalization, but United States Citizenship and Immigration Services ("CIS") denied his application, finding that the Dominican Republic divorce decree granted Garcia's mother, and not his father, "legal custody." Id. at 406. After the CIS Administrative Appeals Office denied his appeal, Garcia filed a petition for a writ of habeas corpus in the district court.2

The district court denied Garcia's petition. It found the Dominican Republic divorce decree highly probative of which parent had custody (Garcia's mother) and therefore concluded that Garcia was unable to demonstrate that he was in his father's sole legal custody when his father naturalized.3 Garcia, 657 F.Supp.2d at 407-08.

Throughout the initial proceedings, Garcia proceeded pro se. When the case came before us, we appointed Garcia pro bono counsel and asked for supplemental briefing.

II.

A.

Prior to its repeal, INA § 321 provided, in pertinent part:

INA § 321, 8 U.S.C. § 1432(a) (1996) (emphasis added), repealed by Child Citizenship Act Of 2000, Title I, § 103(a), 114 Stat. 1632.

The parties agree that when Garcia's father naturalized on April 20, 1996, (1) there was "a legal separation of the parents" and (2) Garcia was under the age of eighteen. The parties disagree as to whether Garcia was in the "legal custody" of his father at the time.

"Legal custody" is a matter of federal law. See Fierro v. Reno, 217 F.3d 1, 4 (1st Cir.2000). Nevertheless, we often look to state law for a rule of decision "[w]here . . . there is no extant body of federal common law in the area of law implicated by the statute." Brissett v. Ashcroft, 363 F.3d 130, 133 (2d Cir.2004). For example, in Brissett, we held that the term "legal separation" contained in the same subsection of the statute requires a formal act, as defined by state law, that alters the marital relationship. Brissett, 363 F.3d at 133-34. In New York, the qualifying "formal act" is either divorce (termination of the marriage) or a formal written or judicial separation, which recognizes the separate existence of the marital parties. See id. We believe a similar reference to state law is appropriate, at least initially, for determining "legal custody," as "[l]egal relationships between parents and children are typically governed by state law, there being no federal law of domestic relations." Fierro, 217 F.3d at 4 (internal quotation marks omitted).

The first step in deciding whether a naturalizing parent has "legal custody" of a child for purposes of derivative citizenship is to determine whether a judicial decree or statutory grant awards custody to the naturalizing parent. Bagot v. Ashcroft, 398 F.3d 252, 268-69 (3d Cir.2005) (Rosenn & Nygaard, concurring). But, notwithstanding a formal termination of the marriage, what if there is no judicial or authorized determination of custody? In Brissett, we indicated that the absence of a formal judicial determination or written separation agreement was fatal to a derivative citizenship claim. Brissett, 363 F.3d at 134. Is an immigrant child of a naturalizing alien denied citizenship because there is no court order or formalized custody agreement? We think not; we are not convinced that our reasoning in Brissett equally applies to determinations of "legal custody."

In Matter of M—, 3 I. & N. Dec. 850 (BIA 1950), a child was born in Czechoslovakia to married parents; the mother was German and the father Jewish. In 1940, the mother "annulled" the marriage and father and daughter immigrated to the United States. They were lawfully admitted, and the father naturalized in 1947 when the child was under the age of eighteen. Id. at 850-51. The "annulment," which the Board of Immigration Appeals ("BIA") treated as a divorce, made no provision for custody, but the mother had surrendered custody to the father. Id. at 851, 854.

The BIA held:

Id. at 856. We "accord substantial deference to the BIA's interpretations of the statutes and regulations that it administers." Brissett, 363 F.3d at 133. Moreover, Matter of M— has been the law for sixty-one years without congressional intervention.4 The BIA's interpretation, thus, has substantial persuasive weight. See Zhang v. Holder, 617 F.3d 650, 662 (2d Cir.2010) (citing Commodity Futures Trading Comm'n v. Schor, 478 U.S. 833, 846, 106 S.Ct. 3245, 92 L.Ed.2d 675 (1986)) (other citations omitted).

Decisions about the marital relationship tend to be final; custody decisions, in contrast, tend to be fluid and frequently change depending on the parents' situations and well-being. See Bagot, 398 F.3d at 270 (Rosenn & Nygaard, concurring). Parents' "agreement to transfer legal custody [is] within the purview of their authority and . . . it is not necessary for parents to come into court to change or amend a de[c]ree of divorce every time they . . . jointly make a major decision concerning the care and custody of their children." Tabucbuc v. Ashcroft, 84 Fed. Appx. 966, 969 (9th Cir.2004) (internal quotation marks omitted) (unpublished memorandum).

Requiring a formal act to change custody—something more than mere agreement—is counterintuitive to the attempts that parents make following a divorce to conduct their lives and those of their children with one goal: the children's best interest. Moreover, in the absence of a judicial determination giving one parent sole custody of the child, each parent generally retains the rights and responsibilities that come with parenthood. N.Y. Dom. Rel. Law § 81 (McKinney 2010); see also 45 N.Y. Jur.2d Dom. Rel. § 333.

Our holding today is consistent with our decision in Brissett. Divorce and judicial separation are inherently different from custody decisions. Bagot, 398 F.3d at 267; see also Morgan v. Att'y Gen., 432 F.3d 226, 234 (3d Cir.2005) (recognizing after Bagot that in contrast to "legal custody," "legal separation" does require a "formal governmental action"). The BIA itself has recognized as much. Compare Brissett, 363 F.3d at 133-34 (recognizing that the BIA interprets "legal separation" to require a formal act), with Matter of M—, 3 I. & N. Dec. at 856 (BIA's interpretation that "actual uncontested custody" can constitute "legal custody").

B.

In his supplemental brief, Garcia argues that New York would not recognize the Dominican Republic custody award and that if the Dominican custodial decree is unenforceable, the parent with actual uncontested custody is the parent with "legal custody" for the purpose of evaluating his derivative citizenship claim. We agree.

At the time that Garcia's mother secured the divorce, Garcia and his family resided in New York and had resided there for four years; New York was their "home state." At that time, New York had enacted the Uniform Child Custody Jurisdiction Act ("UCCJA").5 Pursuant to the UCCJA, New York would not even consider recognizing a foreign custody award unless the foreign law substantially complied with the UCCJA.6 N.Y. Dom. Rel. Law § 75-n (McKinney 1987); N.Y. Dom. Rel. Law § 75-w (McKinney 1987). As the New York Court of Appeals explained, the UCCJA required "[m]aximum rather than minimum contacts with the State." Vanneck v. Vanneck, 49 N.Y.2d 602, 610, 427 N.Y.S.2d 735, 404 N.E.2d 1278 (1980).

It is quite clear that New York had jurisdiction to determine custody, not the Dominican Republic. New York was Garcia's home state when his mother secured the divorce; his family had lived in New York for four years prior to the divorce. Moreover, the record reflects that no other jurisdictional basis was present. Therefore, the Dominican Republic custodial award was not made in "substantial accordance" with the UCCJA. Garcia is correct; New York would not recognize the award.7

This case thus turns then on who had "actual uncontested custody" of Garcia when his father naturalized. Two predominant indicators of "actual uncontested custody" are (i) the child's physical residence, and (ii) consent to custody by the non-custodial parent. See Bagot, 398 F.3d at 267.

In the district court, Garcia, acting as his own counsel, presented largely uncontradicted evidence that he was in his father's "actual uncontested custody" when his father naturalized. When Garcia's father became a citizen, he resided at 201 West 109th Street, Basement Apartment. The affidavits of Garcia and each of his parents provide unrebutted evidence that Garcia resided with both parents at that address from 1989 to at least August 1994.

A middle school abstract (procured by Garcia's pro bono counsel and submitted with this appeal) confirms that Garcia resided at 201 West 109th Street, Basement Apartment, during the 1993 school year. The affidavits of Garcia and his mother each discuss her move out of the family residence in August 1994, leaving Garcia with his father at 201 West 109th Street, and that Garcia's father was "legally, financially, [and] physically responsible for him." His parents contended that they had agreed that Garcia would remain with his father and not move out with his mother. The affidavits are further corroborated by a 2003 U.S. Alien Change of Address form completed by Garcia, which lists Garcia's "OLD address"—i.e., up until 2003—as his father's. Garcia alleges that this piece of evidence connects the dates between the school records from the 1990s through and past 1996 (when his father naturalized).

Before the district court, the Government pointed out that Garcia's father's 1988 and 1992 tax returns either listed Garcia as a dependent without providing his address, or indicated that he had no dependents.8 It also argued that in 1993, Garcia's father submitted an affidavit in support of his second wife's visa application that listed no dependents.9 In addition, Garcia's father's naturalization application omitted Garcia's address, an omission that the Government argues means that Garcia must have lived with his mother.10

In our view, there is a genuine dispute of material fact about which parent (if either) had uncontested custody of Garcia when his father naturalized. The Government and district court relied almost entirely upon the Dominican Republic divorce decree to resolve the matter; without the divorce decree, the Government has introduced very little evidence to contradict Garcia's claim. It is the district court, however, that must weigh the probative value of Garcia's and the Government's evidence. 8 U.S.C. § 1252(b)(5)(B) (2006).

Garcia now has the benefit of appointed counsel, who has diligently searched for and found additional records—such as Garcia's school records—that shed further light on the issue of actual uncontested custody. Further, when acting pro se, Garcia was detained at the Batavia immigration detention center, which severely limited his ability to provide the court with documents and other evidence that might assist it in making its determination of which, if either, of Garcia's parents had actual uncontested custody of him when his father naturalized. Thus, we instruct the district court to hold a hearing under 8 U.S.C. § 1252(b)(5)(B) (2006).

The district court should conduct this hearing in the same manner that it conducts any other evidentiary hearing. The district court should give Garcia's appointed counsel (and the Government) a fair opportunity to supplement the record, if necessary, with any additional evidence, including witness testimony, that is material to the custody issue.

III.

We appoint Garcia counsel in the district court. We may appoint an unrepresented party counsel if we find the factors set forth in Hodge v. Police Officers, 802 F.2d 58 (2d Cir.1986), satisfied. These factors include: (1) whether the party's claim has substantial merit; (2) whether the nature of the factual issues requires an investigation, and whether the party's ability to investigate is inhibited; (3) whether the claim's factual issues turn on credibility, which benefits from the skills of those trained in presentation of evidence and cross-examination; (4) the party's overall ability to present its case; and (5) whether the legal issues presented are complex. Hodge, 802 F.2d at 60-61. We find that all of these factors favor appointing Garcia counsel in the district court. Therefore, we instruct the district court to appoint Garcia counsel.11 28 U.S.C. § 1915(e) (2006); Hendricks v. Coughlin, 114 F.3d 390, 393-94 (2d Cir.1997); Hodge, 802 F.2d at 60-61.

IV.

We have reviewed Garcia's other claims on appeal and find them to be without merit. To conclude, we VACATE and REMAND the district court's order and judgment. We instruct the district court to hold a hearing consistent with this opinion, and we appoint Garcia counsel for the district court proceedings. We continue Garcia's stay of removal pending further proceedings in this court.

VACATED and REMANDED.

APPENDIX

N.Y. Dom. Rel. Law § 75-d (McKinney 1987) (emphasis added).