On June 14, 1973, petitioner Ramón Antonio Duarte-Ceri (“Duarte”) was born in the Dominican Republic. On June 14, 1991 — eighteen years later to the day— Duarte’s mother was naturalized as a U.S. citizen in New York. The parties and the Immigration Judge below assumed that Duarte was born in the evening and that his mother was naturalized in the morning. The question presented is whether Duarte was still “under the age of eighteen years” when his mother took the naturalization oath. If so, Duarte acquired derivative U.S. citizenship from his mother by operation of law, and he is not subject to removal from the United States. If not, he is not a U.S. citizen, and he will be deported to the Dominican Republic. We hold, on the assumed facts, that Duarte was still “under the age of eighteen years” when his mother was naturalized. Because there has been no factual finding as to the actual timing of Duarte’s birth, however, we transfer the case to the district court for a “new hearing on the nationality claim,” pursuant to 8 U.S.C. § 1252(b)(5)(B).
STATEMENT OF THE CASE
A. The Facts
In the proceedings below, the parties assumed the following facts:
Duarte was born in the Dominican Republic on the evening of June 14, 1973. He was admitted to the United States as a lawful permanent resident in 1981, when he was eight years old. On July 24, 1989, *86Duarte’s parents divorced in New York. The divorce decree granted Duarte’s mother, Carmen Paula Duarte, sole custody of Duarte and his younger brother. Duarte was sixteen years old when his mother applied for citizenship on February 5, 1990. Her application was granted on March 15, 1991, and she took the oath of citizenship on the morning of June 14, 1991 — the same day as Duarte’s eighteenth birthday.
Between 1989 and 1995, Duarte was arrested at least three times. In 1990, he was charged with assault, and sentenced as a youthful offender. In 1991, Duarte pled guilty to possessing stolen property. Then, in 1994, Duarte pled guilty to attempted sale of a controlled substance. On April 14, 1995, the Immigration and Naturalization Service served Duarte with an Order to Show Cause, charging that he was subject to deportation as a non-citizen convicted of a controlled substance offense and an aggravated felony. See 8 U.S.C. § 1227(a)(2)(B)(i) (controlled substance conviction); id. § 1227(a)(2)(A)(iii) (aggravated felony conviction). Duarte admitted the allegations against him, and applied for a waiver of excludability. On February 24, 1997, the Immigration Judge (“IJ”) denied the application for a waiver, and ordered Duarte deported to the Dominican Republic. The Board of Immigration Appeals (the “BIA”) affirmed on September 5, 2001.
B. Procedural History
Starting in November 2004, Duarte pursued a variety of procedural strategies to press his argument that he is actually a U.S. citizen by operation of former section 321(a) of the Immigration and Nationality Act (the “INA”), 8 U.S.C. § 1432(a) (1999), repealed by Pub.L. 106-395, § 103(a), 114 Stat. 1631, 1632 (2000). That provision grants derivative citizenship to certain children whose parents are naturalized while they are still “under the age of eighteen years.” Duarte’s mother was naturalized on the morning of June 14, 1991. Duarte argues that he qualifies for derivative citizenship because he was born in the evening, and he did not actually reach the age of eighteen years until the evening of June 14,1991.
Though the BIA did reopen Duarte’s case and remand to the IJ on one occasion to consider this issue, the IJ eventually ruled that the precise hour of birth was not relevant to the derivative citizenship inquiry because Duarte “was 18 when that clock moved past midnight [on June 14, 1991].” As a consequence, the IJ did not make any findings of fact as to what time of day Duarte was born on June 14, 1973. On appeal, the BIA agreed with the IJ that the precise timing was not relevant, concluding that “in computing the child’s age for derivative citizenship purposes under the applicable statute, the designated age of maturity will be attained at 12:01 a.m. on the applicable anniversary day.”
Duarte has also filed an application for citizenship with U.S. Citizenship and Immigration Services (“USCIS”), a federal habeas corpus petition, and several more motions to reopen at the BIA. USCIS denied Duarte’s application, and the Administrative Appeals Office dismissed Duarte’s appeal from the denial. The federal district court dismissed the habeas petition, concluding that it did not have jurisdiction over the matter. Duarte-Ceri v. Napolitano, No. 07 Civ. 500A (RJA), 2009 WL 1806694 (W.D.N.Y. June 23, 2009).
On October 23, 2008, the BIA declined to exercise its sua sponte authority to reopen Duarte’s case another time. Duarte is now before this Court on a petition for review from the BIA’s decision declining to reopen removal proceedings.
*87 DISCUSSION
A. Jurisdiction
Duarte’s claim to derivative citizenship presents an issue of law over which we have jurisdiction. See 8 U.S.C. § 1252(a)(2)(D) (judicial review preserved as to constitutional claims or questions of law); id. § 1252(b)(5)(A) (“If the petitioner claims to be a national of the United States and the court of appeals finds from the pleadings and affidavits that no genuine issue of material fact about the petitioner’s nationality is presented, the court shall decide the nationality claim.”).
Although Duarte’s claim comes to us in the posture of a petition for review from the BIA’s refusal to reopen removal proceedings sua sponte — a discretionary decision that is normally not reviewable by the Courts of Appeals, see Ali v. Gonzales, 448 F.3d 515, 518 (2d Cir.2006) — here, Duarte’s legal claim encounters no jurisdictional obstacle because the Executive Branch has no authority to remove a citizen. An assertion of U.S. “citizenship is thus a denial of an essential jurisdictional fact” in a deportation proceeding. Ng Fung Ho v. White, 259 U.S. 276, 284, 42 S.Ct. 492, 66 L.Ed. 938 (1922); see also Frank v. Rogers, 253 F.2d 889, 890 (D.C.Cir.1958) (“Until the claim of citizenship is resolved, the propriety of the entire proceeding is in doubt.”).
B. Merits
To resolve the legal question presented, we assume the facts assumed by the parties and the IJ below — that Duarte was born the evening of June 14, 1973 and his mother was naturalized the morning of June 14,1991.
To determine whether a petitioner obtains derivative citizenship, the court “applies] the law in effect when [petitioner] fulfilled the last requirement [to qualify].” Ashton v. Gonzales, 431 F.3d 95, 97 (2d Cir.2005). At the time Duarte’s mother received her citizenship in 1991, section 321(a) of the INA provided, in relevant part:
A child born outside the United States of alien parents ... becomes a citizen of the United States upon fulfillment of the following conditions: ...
(3) The naturalization of the parent having legal custody of the child when there has been a legal separation of the parents or the naturalization of the mother if the child was born out of wedlock and the paternity of the child has not been established by legitimation; and if
(4) Such naturalization takes place while such child is unmarried aand under the age of eighteen years; and
(5) Such child is residing in the United States pursuant to a lawful admission for permanent residence at the time of the naturalization of the parent ... naturalized under clause ... (3).
8 U.S.C. § 1432(a) (emphasis added) (repealed 2000).1
Duarte meets condition (3) because at the time his mother was naturalized, she had sole legal custody of him under a valid divorce decree. He also meets condition (5) because he began to reside in the United States as a lawful permanent resident in 1981, when he was eight years old. In terms of condition (4), Duarte was unmarried at the time of his mother’s naturalization. The question we must address is whether Duarte still qualified as “under the age of eighteen years” when his mother was naturalized on the morning of his eighteenth birthday.
*88The language of the statute is ambiguous. The phrase “under the age of eighteen years” is susceptible to two meanings. On one hand, it could refer to an applicant who has not yet reached the eighteenth anniversary of his birth. Under this interpretation, Duarte’s claim fails, for he had reached the eighteenth anniversary of his birth when his mother was naturalized. On the other hand, it could refer to an applicant who has not yet lived in the world for eighteen years. Under this interpretation, on the assumed facts, Duarte’s claim prevails, for, as a matter of biological fact, on the morning of June 14, 1991, Duarte had not yet lived for eighteen years. Rather, he had lived approximately seventeen years, 364 days, and twelve hours.
Faced with two plausible readings of the statutory language, and a congressional direction to “decide the nationality claim,” we conclude that the circumstances of this case and principles of statutory construction require us to adopt the interpretation that preserves rather than extinguishes citizenship.2
First, on the assumed facts, as a factual matter Duarte had not lived eighteen years when his mother was naturalized. Under the BIA’s decision, he would be deported only because of the application of a legal fiction — that he turned eighteen years of age at the stroke of midnight on the eighteenth anniversary of his birth.
Second, the Supreme Court has long held that “whenever it becomes important to the ends of justice, ... the law will look into fractions of a day, as readily as into the fractions of any other unit of time.” Town of Louisville v. Portsmouth Sav. Bank, 104 U.S. 469, 474, 26 L.Ed. 775 (1881); accord Taylor v. Brown, 147 U.S. 640, 645-46, 13 S.Ct. 549, 37 L.Ed. 313 (1893) (“as to the general doctrine that the law does not allow of fractions of a day, it is settled that, when substantial justice requires it, courts may ascertain the precise time when ... an act [is] done”). The legal fiction that a day is indivisible is a rule of convenience that is satisfactory only as long as it does not operate to destroy an important right. See In re Gubelman, 10 F.2d 926, 930 (2d Cir.1925). “There is no indivisible unity about a day which forbids us, in legal proceedings, to consider its component hours, any more than about a month, which restrains us from regarding its constituent days. The law is not made of such unreasonable and arbitrary rules.” Portsmouth Sav. Bank, 104 U.S. at 475. In the bankruptcy context, for example, courts have long consid*89ered fractions of days to determine certain rights.3
Third, here, it is important to the ends of justice to parse the day into hours, for “the most precious right” of citizenship is at stake. Kennedy v. Mendoza-Martinez, 372 U.S. 144, 159, 83 S.Ct. 554, 9 L.Ed.2d 644 (1963). “The stakes are indeed high and momentous,” Delgadillo v. Carmichael, 332 U.S. 388, 391, 68 S.Ct. 10, 92 L.Ed. 17 (1947), for “deportation is a drastic measure and at times the equivalent of banishment or exile.” Fong Haw Tan v. Phelan, 333 U.S. 6, 10, 68 S.Ct. 374, 92 L.Ed. 433 (1948). If we abide by the legal fiction that a day is indivisible for these purposes, then Duarte forfeited his right to be a U.S. citizen and he will be deported. And although he grew up in the United States and his mother, brother, and children are all U.S. citizens, he will be separated from them.
We cannot, and do not, contest that in “everyday speech and writing,” people often use the phrases “under the age of eighteen” and “before one’s eighteenth birthday” interchangeably. This linguistic imprecision is a matter of convenience— related to the legal fiction that a day is indivisible — and in the vast majority of contexts, it simply does not matter one way or another. In particular, it is significant that in most contexts, an individual gains a right or privilege when he reaches the “age of eighteen” — to take the dissent’s examples: he is permitted to buy lottery tickets, work in a public school, sell alcoholic beverages, visit strip clubs, and, if he is a United States citizen, he may vote or serve as a juror. Here, Duarte stands to suffer a great loss, predicated on a rule of convenience. That it may be somewhat inconvenient to calculate Duarte’s precise age should not be a deterrent because circumstances like these are not common occurrences.
To the extent that the dissent argues that “the ends of justice” is too malleable a standard for courts to apply, we disagree. Courts apply this standard in contexts as varied as the grant of a continuance in a criminal prosecution, see 18 U.S.C. § 3161(h)(7)(A), the application of the hearsay rule, see Chambers v. Mississippi, 410 U.S. 284, 302, 93 S.Ct. 1038, 35 L.Ed.2d 297 (1973), the adjudication of successive habeas claims, see Schlup v. Delo, 513 U.S. 298, 320, 115 S.Ct. 851, 130 L.Ed.2d 808 (1995), and the relaxation of procedural rules, see Schacht v. United States, 398 U.S. 58, 64, 90 S.Ct. 1555, 26 L.Ed.2d 44 (1970). In short, courts are entrusted with determinations based on the “ends of justice” each and every day; indeed, such determinations are at the heart of judicial decision-making, preventing mechanical interpretations of rules from devolving into injustice.
In the immigration context, there is a long-standing presumption to construe “any lingering ambiguities” in favor of the petitioner. INS v. Cardoza-Fonseca, 480 U.S. 421, 449, 107 S.Ct. 1207, 94 L.Ed.2d 434 (1987). Here, Congress enacted the *90derivative citizenship statute to ensure that “alien children whose real interests were located in America with their custodial parent, and not abroad, should be automatically naturalized.” Bustamante-Barrera v. Gonzales, 447 F.3d 388, 397 (5th Cir.2006) (internal quotation marks omitted). The statute “implements the underlying intention of our immigration laws regarding the preservation of the family unit.” H.R.Rep. No. 82-1365, at 24 (1952), as reprinted in 1952 U.S.C.C.A.N. 1653, 1680. It is consistent with Congress’s remedial purposes, therefore, to interpret the statute’s ambiguity with leniency, and we should interpret the statute here in a manner that will keep families intact.
It is noteworthy that the statute did not provide that a parent’s naturalization had to take place “before the child attains his eighteenth birthday” or “prior to the child’s eighteenth birthday.” This language would be unambiguous because the entirety of June 14, 1991 was Duarte’s eighteenth birthday — from 12:00 a.m. until 11:59 p.m. No matter what time Duarte was born, his mother was not naturalized “prior to his eighteenth birthday.” Indeed, Congress has actually employed similar unambiguous age-related phrasing elsewhere in the INA. See, e.g., 8 U.S.C. § 1483(b) (“A national ... shall not be deemed to have lost United States nationality by the commission, prior to his eighteenth birthday, of any of [enumerated acts].”); id. § 1101(a)(27)(I)(i) (referring to certain conditions that must be performed “no later than [one’s] twenty-fifth birthday” to qualify as a “special immigrant”); see also 18 U.S.C. § 5031 (“For the purposes of this chapter, a ‘juvenile’ is a person who has not attained his eighteenth birthday.”). On the other hand, if the words “under the age of eighteen years” are given their literal meaning, Duarte was eligible to become a citizen derivatively because he was still “under the age of eighteen years” when his mother was naturalized — he apparently had lived only for approximately seventeen years, 364 days, and twelve hours.
We cannot simply dismiss the difference in language between former INA § 321(a) (“a child ... under the age of eighteen years”) and 18 U.S.C. § 5031 (“a person who has not attained his eighteenth birthday”) as inadvertent or immaterial. In 1948, Congress took the affirmative step of eliminating ambiguity in 18 U.S.C. § 5031 by amending it to replace the phrase “seventeen years of age or under” with “who has not attained his eighteenth birthday.” 18 U.S.C. § 5031 Notes to 1948 Acts. It did so after a district judge wrote to express “the necessity of a definite fixing of the age of [a] juvenile.” Id. Congress could have made a similar change to the statutory language here, but it did not.
In 1952, the BIA, in a published decision, interpreted a citizenship statute that required a child born to U.S. citizens outside the United States to take up residence in the United States “by the time he reaches the age of 16 years” to retain his U.S. citizenship. See In re L-M- and C-Y-C-, 4 I. & N. Dec. at 618 (quoting Nationality Act of 1940 § 201(g)). The two appellants returned to the United States on their sixteenth birthday, one at 4 a.m. and the other at 8 a.m. The government argued that they were too late because they had turned sixteen at 12:01 a.m., and thus arrived after they had reached the age of sixteen. Id. The BIA rejected the argument, and ruled that it was sufficient that the appellants arrived on the day they turned sixteen. It held that, when considering “the great privilege of citizenship,” “the method of arriving at the computation is to be in the interest of the person affected by it.” Id. at 620. The BIA concluded that:
*91A divestiture of American citizenship should not be predicated upon an ambiguity. Where the language of the statute is capable of more than one construction, that construction is favored by the law which will best preserve a right or prevent a forfeiture.
Id. at 621.4
These principles apply with equal force here. Where a statute conferring citizenship derivatively is susceptible of two interpretations, the only difference being the divisibility of a unit of time, the law favors the interpretation that preserves the right of citizenship over the interpretation that forfeits it. On the assumed facts, we conclude that Duarte was “under the age of eighteen years” when his mother was naturalized.
C. Transfer
In the context of removal proceedings, claims that a petitioner is a U.S. national are governed by 8 U.S.C. § 1252(b)(5). The court of appeals “shall” decide such nationality claims if it “finds from the pleadings and affidavits that no genuine issue of material fact about the petitioner’s nationality is presented.” 8 U.S.C. § 1252(b)(5)(A). If, however, the court of appeals concludes that “a genuine issue of material fact about the petitioner’s nationality is presented, the court shall transfer the proceeding to the district court of the United States for the judicial district in which the petitioner resides for a new hearing on the nationality claim and a decision on that claim as if an action had been brought in the district court under section 2201 of Title 28.” 8 U.S.C. § 1252(b)(5)(B). We determine the existence of a genuine issue of material fact for these purposes using the same principles employed on a Rule 56 motion for summary judgment. See Agosto v. INS, 436 U.S. 748, 754, 98 S.Ct. 2081, 56 L.Ed.2d 677 (1978); Ayala-Villanueva v. Holder, 572 F.3d 736, 738 (9th Cir.2009).
In the removal proceedings, the parties and the IJ assumed that Duarte was born the evening of June 14, 1973, but the IJ determined there was no need for factual findings in that respect because the time of the birth was legally insignificant. Duarte submitted affidavits from his mother as well as a nurse who purportedly participated in the delivery stating that Duarte was born at approximately 9 p.m. on June 14, 1973. The Government did not submit any evidence to contradict the affidavits, but there was no reason for it to do so because of the IJ’s ruling on the legal question.5 The issue is now squarely presented because of our conclusion that the precise timing of Duarte’s birth on June 14, 1973, is relevant. Accordingly, we transfer the matter to the United States District Court for the Western District of New York for a new hearing on Duarte’s nationality claim, pursuant to 8 U.S.C. § 1252(b)(5)(B).6
CONCLUSION
For the reasons set forth above, we TRANSFER this proceeding to the United *92States District Court for the Western District of New York, and HOLD IN ABEYANCE his petition for review.
. Subsections (1) and (2) are not relevant to Duarte’s petition.
. Although the Government did not argue in its brief that the BIA's interpretation of former INA § 321(a) was entitled to deference under Chevron, U.S.A., Inc. v. Natural Res. Def. Council, Inc., 467 U.S. 837, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984), it did so in a subsequent submission pursuant to Rule 28(j) of the Federal Rules of Appellate Procedure. We reject the argument. "While the BIA’s interpretation of immigration statutes is generally entitled to Chevron deference, interpretations in non-precedential unpublished BIA decisions ... are not so entitled.” Dobrova v. Holder, 607 F.3d 297, 301 (2d Cir.2010) (citing Mendis v. Filip, 554 F.3d 335, 338 (2d Cir.2009)). The BIA's 2008 decision in Duarte's case is a non-precedential, unpublished decision. Indeed, the BIA has never formally codified the view expressed in its decision in this case — namely, that the "age of maturity will be attained at 12:01 a.m. on the applicable anniversary day (21st, 18th, or 16th) of the child’s birth.” In re Ramon Antonio Duarte-Ceri, No. A37 161 007 (B.I.A. Nov. 21, 2005). Instead, in the BIA’s only published decision in which the agency encountered the situation we face today — where a crucial event occurs on the same day as the applicant's birthday — the BIA took a lenient view. See Matter of L-M- and C-Y-C-, 4 I. & N. Dec. 617 (B.I.A. Feb. 20, 1952). We discuss this case more thoroughly infra.
. See, e. g., Vaneo Trading, Inc. v. Monheit (In re K Chemical Corp.), 188 B.R. 89, 95-96 (Bankr.D.Conn.1995) (holding that although fractions of a day are generally disregarded in court proceedings, "the fractionalization approach is uniformly utilized in a wide range of Bankruptcy Code disputes involving temporal concepts”); In re Dejay Stores, Inc., 220 F.Supp. 497, 501 (S.D.N.Y.1963) (where two bankruptcy petitions were filed two minutes apart on the same day, holding that “legal fiction that a day is an indivisible period of time” should be disregarded where ignoring the time differential would deprive first petitioning creditors of right to nominate and elect trustee). Though the dissent argues that bankruptcy is the only context in which the law parses days, as we discuss herein, this is not correct.
. The dissent notes that this case has not frequently been cited. Likely, this is because it is such a rare circumstance that the final qualifying citizenship event occurs on the same day as the applicant's crucial birthday.
. We note that in its brief on appeal, the Government states that "there is no genuine issue of material fact regarding Duarte’s citizenship claim” and that “the issues presented on this citizenship claim are purely legal.” Under the circumstances, we do not construe this as a concession that Duarte in fact was bom in the evening on June 14, 1973.
. The most recent indication in the record is that Duarte "resides” at the Buffalo Detention Facility in Batavia, New York, in the Western District of New York.