Opinion by Judge DAVID R. THOMPSON; Dissent by Judge BERZON.

Petitioner Nathaniel Flores Pazcoguin petitions for review of the Board of Immigration Appeals’ (“BIA”) final order of deportation, finding him excludable from the United States because he: (1) admitted acts that constitute the essential elements of a controlled substance violation, Immigration and Nationality Act (“INA”) § 212(a)(2)(A)(i)(II), 8 U.S.C. § U82(a)(2)(A)(i)(II); and (2) was an alien without a valid immigrant visa, INA § 212(a)(7)(A)(i)(I), 8 U.S.C. § 1182 (a)(7)(A)(i)(I).

We have jurisdiction under 8 U.S.C. § 1105a(a), as amended by section 309(c) of the Illegal Immigration Reform and Immigrant Responsibility Act of 1996 (“IIRIRA”). See Avetova-Elisseva v. INS, 213 F.3d 1192 , 1195 n. 4 (9th Cir. 2000). 1 Our jurisdiction is not foreclosed *1212 by IIRIRA § 309(c)(4)(G) which precludes judicial review in cases where an alien is inadmissible or deportable by reason of having committed a controlled substance offense. See Alfaro-Reyes v. INS, 224 F.3d 916 , 921-22 (9th Cir.2000); Magana-Pizano v. INS, 200 F.3d 603, 607 (9th Cir.1999). We have repeatedly held that we retain jurisdiction to determine whether an alien in fact committed acts that would trigger IIRIRA § 309(c)(4)(G). See, e.g., Dillingham v. INS, 267 F.3d 996, 1003-05 (9th Cir.2001); Ye v. INS, 214 F.3d 1128, 1131 (9th Cir.2000); Lujan-Armendariz v. INS, 222 F.3d 728, 734 (9th Cir.2000); Albillo-Figueroa v. INS, 221 F.3d 1070, 1073 (9th Cir.2000). Because the central issue here is whether Pazco-guin in fact admitted to committing the essential elements of a controlled substance violation, we have jurisdiction. We deny the petition for review.

Background

Pazcoguin, a native and citizen of the Philippines, was issued a United States immigrant visa by the American Embassy in Manilla, as the unmarried son of a lawful permanent resident. As part of that visa issuance process, Pazcoguin underwent a psychiatric examination by Dr. Leilani L. Demeterio to determine whether he had a personality disorder. During the examination, Pazcoguin told Dr. Deme-terio that he had used marijuana from 1984 to 1987, until he was approximately 21 years old. Dr. Demeterio issued a psychiatric report which noted Pazcoguin’s marijuana use. The consular officer in the American Embassy in Manilla reviewed the medical report containing Pazcoguin’s admission of using marijuana, but nonetheless issued him an immigrant visa.

Pazcoguin subsequently arrived at the Honolulu International Airport and applied for admission into the United States. When asked by Inspector James Myers about his statements to Dr. Demeterio relating to his marijuana use, Pazcoguin provided a sworn statement in which he repeated the admissions he had made. Pazcoguin was paroled into the United States for deferred inspection.

On a later date, Pazcoguin appeared with counsel for deferred inspection before Inspector Judith Kalin. During this inspection proceeding, he asserted the right against self-incrimination under the Fifth Amendment and refused to answer any questions about his use of marijuana. Inspector Kahn terminated the proceeding and determined that Pazcoguin was ex-cludable from the United States because of his prior use of marijuana in the Philippines.

An Immigration Judge heard the case and found Pazcoguin excludable. The BIA dismissed his appeal. The BIA held that Pazcoguin was excludable because he admitted using marijuana while living in the Philippines, and that constituted a controlled substance offense under Philippine law. The BIA also held that, because this rendered him inadmissable at the time his visa was issued, he was excludable on the additional ground that he did not have a valid immigrant visa. Pazcoguin timely petitioned this court for review.

Discussion

A. Burden of Proof To Establish Admissibility into the United States

Pazcoguin’s possession of the immigrant visa issued by the consular officer in the Philippines constituted a prima fa-cie case of his admissibility into the United States. See Matter of Walsh and Pollard, 20 I & N Dec. 60, 63 , 1988 WL 312511 (BIA 1988); INA § 221(h), 8 U.S.C. § 1201 (h); 4 CHARLES GORDON, ET *1213 AL„ IMMIGRATION LAW AND PROCEDURE § 55.09[3][c] (rev. ed.2001). Pazcoguin argues, however, that the visa did more than this. He contends the visa established his admissibility and foreclosed any “second look” by an immigration officer at the port of entry. He points out that the consular officer in the Philippines who issued the visa did so after considering all of the facts pertaining to his use of marijuana. He argues the decision to issue the visa was a decision by “the U.S. Government’s own agent” and the government “should not be permitted to later change its mind at the gates” by an immigration officer rejecting the visa and denying Pazcoguin’s entry into the United States. We are unpersuaded by Pazco-guin’s argument. The INA requires a “double check” of the alien’s qualifications by immigration officers at the port of entry. See INA § 235(a), 8 U.S.C. § 1225 (a).

Because Pazcoguin established a prima facie case of admissibility, the burden of production shifted to the INS to produce “some evidence” to show that he was not admissible. See Matter of Walsh and Pollard, 20 I & N Dec. at 63 . If the INS satisfied this burden, Pazcoguin then had to rebut the INS’s evidence to satisfy his ultimate burden that he was “not inad-missable under any provision of’ the INA. INA § 291, 8 U.S.C. § 1361 .

The BIA determined that the INS satisfied its burden of production by presenting three pieces of evidence: (1) Dr. Demeter-io’s medical report stating that Pazcoguin admitted 9052 having used marijuana, (2) Inspector Myers’ statement that Pazcoguin confirmed this admission, and (3) Inspector Kalin’s statement that she had attempted to question Pazcoguin about his drug use, but he refused to answer her questions. Pazcoguin did not rebut this showing. Instead, he invoked the Fifth Amendment and refused to answer any of Inspector Kalin’s questions about his use of marijuana. According to the BIA, this resulted in Pazcoguin’s failure to carry his ultimate burden of establishing his admissibility.

Pazcoguin challenges the showing made by the INS in response to his prima facie case. He contends his admissions were not sufficient to warrant his exclusion, and in any event, they should not have been considered because they were invalidly obtained. Therefore, he argues, the INS failed to refute his prima facie case and he is entitled to be admitted into the United States. Pazcoguin also raises two constitutional challenges. We consider each of his contentions in turn.

B. Do Pazcoguin’s Admissions Warrant Exclusion?

INA § 212(a)(2)(A)(i)(II) provides that an alien is “inadmissable” (with certain exceptions not relevant here) if the alien (1) was “convicted of,” or (2) “admits having committed,” or (3) “admits committing acts which constitute the essential elements of ... a violation of ... any law or regulation of ... a foreign country relating to a controlled substance ....” In this case, we deal only with the third prong of this statute and ask whether Pazcoguin’s admission of marijuana use is an admission of conduct which constitutes the essential elements of a violation of Philippine law. 2

*1214 The relevant Philippine law is Republic Act No. 6245, known as the Dangerous Drug Act of 1972. Section 8 of this act provides:

Indian hemp is defined in Section 2(i) of the Act as marijuana.

The first element of the subject offense is possession or use of marijuana. It is undisputed that Pazcoguin admitted using marijuana. So long as that admission may be considered, an issue we analyze hereafter, the possession/use element of the statute is satisfied. Pazcoguin’s admitted use of marijuana over several years also satisfies the mens rea requirement of intended possession. See United States v. Chua Lui 26 Phil. 94 , 1913 Phil. S.Ct. LEXIS 1085 (1913) (intention to possess is mens rea requirement of drug possession statute); United States v. Gan Lian Po, 34 Phil. 880 , 1917 Phil. S.Ct. LEXIS 1498 (1916) (mens rea requirement not satisfied where defendant had no knowledge that he had a prohibited drug in his possession).

The remaining question is whether the “unless authorized by law” clause in the statute is an essential element of the offense. If it is, Pazcoguin’s admissions are not sufficient to establish that he admitted committing the essential elements of the applicable Philippine controlled substance offense because he did not say his marijuana use was “[unjauthorized by law.”

Having reviewed Philippine law, we conclude that the “unless authorized by law” clause is not an element of the offense, but rather a defense. In Philippines v. Renato de los Reyes y Solteo, 1994 Phil. S.Ct. LEXIS 4884 (1994), the defendant was convicted of selling drugs in violation of the Philippine Dangerous Drug Act. The provision there contained an exception similar to the one in the present case: “without any authority of law.” The Philippine Supreme Court held that the clause was a defense and not an element of the offense, and the burden was on the defendant, not the prosecutor to “prove that he falls under the protective mantle of the exemption.” Id. at *23 .

The rule that such an exception in a criminal statute is a defense and not an element of the offense is a long-standing one under Philippine law. See, e.g., Philippines v. Cadabis, 97 Phil. 829 , 1955 Phil. S.Ct. LEXIS 1264 (1955) (“In a prosecution for violation of a statute which contains an excepting clause,” the “exception is for the defendant to prove — not for the prosecution to disprove”); United States v. Yao Sim, 31 Phil. 301 , 1915 Phil. S.Ct. LEXIS 1282 (1915); United States v. Chan Toco, 12 Phil. 262 , 1908 Phil. S.Ct. LEXIS 1902 (1908). 3

Because under Philippine law the “unless- authorized by law” clause is a defense, Pazcoguin need not have stated that his marijuana use was unauthorized in order to admit the essential elements of the offense. We therefore hold that his ad *1215 missions are sufficient under the INA to establish that he committed acts which constitute the essential elements of the violation of the applicable Philippine controlled substance law and, thus, to warrant his exclusion.

This holding is consistent with how our court, in other contexts, has defined “elements of a crime.” In United States v. Innie, 7 F.3d 840 (9th Cir.1993) we defined “elements of a crime” as the “ ‘constituent part[s] of the offense which must be proved by the prosecution in every case to sustain a conviction under a given statute.’ ” Id. at 850 (quoting United States v. Sherbondy, 865 F.2d 996, 1010 (9th Cir.1988)) (emphasis added); see also United States v. Fulford, 267 F.3d 1241, 1250 (11th Cir.2001) (“When Congress uses a word like ‘element’ in a federal criminal statute without otherwise defining it, we assume that the word carries its accepted meaning in the criminal law. At common law the word ‘element’ refers to a constituent part of a crime which must be proved by the prosecution to sustain a conviction.”) (quotation omitted). The phrase “essential element of a crime” also appears in our cases in a variety of contexts. We have never used the phrase to encompass an affirmative defense. See, e.g., United States v. Carranza, 289 F.3d 634, 641-42 (9th Cir.2002); United States v. Du Bo, 186 F.3d 1177, 1180 (9th Cir.1999); United States v. King, 122 F.3d 808, 810 (9th Cir.1997); Goldeshtein v. INS, 8 F.3d 645, 647 (9th Cir.1993).

The dissent also argues that because Pazcoguin did not state that his marijuana use was unauthorized by law, he “may not have committed a crime;” thus, he should not be found inadmissable. This argument overlooks the fact that the applicable statute contains three independent grounds for exclusion. The dissent’s view might be plausible if the INS had sought to exclude Pazcoguin based on the second ground of exclusion — i.e., that he “admitted] having committed a controlled substance violation.” See INA § 212(a)(2)(A)(i)(II). But that is not this case. The INS relies on the statute’s third ground of exclusion— i.e., that Pazcoguin “admitted] committing acts which constitute the essential elements of’ a controlled substance violation. See id. Pazcoguin did in' fact make those admissions. Thus, he falls within the statute’s third ground for exclusion, and we will not render that ground superfluous by reading it out of the statute. See United States v. Smith, 155 F.3d 1051, 1058 (9th Cir.1998) (statute should be construed to give effect to “every clause and word”). We next consider whether Pazcoguin’s admissions were validly obtained.

C. Were Pazcoguin’s Admissions Validly Obtained?

Pazcoguin contends that his admissions were not validly obtained because they were not obtained in conformity with the procedural safeguards established by BIA case law. The BIA, he argues, abused its discretion by fading to apply its own precedents when it relied on his admissions and affirmed the exclusion order.

We review the BIA’s interpretation of its case law under the abuse of discretion standard, and will not disturb its interpretation unless the BIA “acted arbitrarily, irrationally or contrary to law. The BIA acts arbitrarily when it disregards its own precedents and policies without giving a reasonable explanation for doing so.” Braun v. INS, 992 F.2d 1016, 1019 (9th Cir.1993) (internal citation omitted) (citing Israel v. INS, 785 F.2d 738, 740 (9th Cir.1986)).

BIA case law has established three requirements which must be met for an admission to qualify as having been validly obtained. First, the admitted conduct must constitute the essential elements of a *1216 crime in the jurisdiction where it occurred. Second, the applicant for admission must have been provided with the definition and essential elements of the crime prior to his admission. Third, his admission must have been voluntary. See Matter of K, 7 I & N Dec. 594 , 598, 1957 WL 10581 (BIA 1957); Matter of J, 2 I & N Dec. 285 , 1945 WL 5557 (BIA 1945).

1. The admitted conduct must constitute the essential elements of a crime in the Philippines.

Pazcoguin contends the INS failed to establish that his admitted conduct constituted the essential elements of a crime under Philippine law, because the INS faded to produce an expert witness on that subject. We disagree. The determination of foreign law is a question of law. See Fed.R.Civ.P. 44.1; DP Aviation v. Smiths Indus. Aerospace & Def. Sys., 268 F.3d 829 , 846 & n. 16 (9th Cir.2001). In interpreting Philippine law, we “may consider any relevant material or source, including testimony, whether or not submitted by a party or admissible under the Federal Rules of Evidence.” Fed R. Civ. P. 44.1. While expert testimony may be useful, it is not “an invariable necessity in establishing foreign law, and indeed, federal judges may reject even the uncontradicted conclusions of an expert witness and reach their own decisions on the basis of independent examination of foreign legal authorities.” Access Telecom, Inc. v. MCI Telecomms. Corp., 197 F.3d 694, 713 (5th Cir.), cert. denied, 531 U.S. 917 , 121 S.Ct. 275 , 148 L.Ed.2d 200 (2000). “In some cases foreign law may be proved by reference to authorities; in others foreign law experts may testify.” DP Aviation, 268 F.3d at 848. Here, we have reviewed the Philippine statute at issue and have conducted our own research into Philippine law. Having considered these sources, we are satisfied that Pazcoguin’s admitted use of marijuana constituted the essential elements of a crime prohibited by Philippine Republic Act No. 6425.

Pazcoguin next argues that his conduct was not punishable as a crime at the time he sought admission into the United States because the statute of limitations for his prosecution had expired. This argument misses the mark. The applicable INA statute, § 212(a)(2)(A)(i)(II), does not require the conduct to be punishable as a crime at the time an applicant seeks admission. In fact, the statute “precluded] immigration officials from determining guilt or innocence.” Braun, 992 F.2d at 1019 .

2. The applicant must have been provided with a definition and the essential elements of the offense prior to his admission.

Pazcoguin next argues that his admissions were not validly obtained because he was not provided with a definition and the essential elements of the Philippine crime of possession or use of marijuana prior to making his admissions. See Matter of K, 7 I & N Dec. at 596-98.

The BIA decision in this case fails to address whether the INS complied with this BIA requirement. The BIA decision simply explains that:

While it is true that Pazcoguin refused to answer Inspector Kalin’s questions during the inspection process, the issue is whether the INS carried its burden of production after Pazcoguin established his prima fa-cie case, and that depends on whether Pazcoguin’s admission to Dr. Demeterio during his medical examination in the Philippines or his admission to Inspector *1217 Myers during his interview in Honolulu may be considered. As explained below, we conclude that the admission to Dr. Demeterio may be considered but the admission to Inspector Myers may not.

With regard to Pazcoguin’s admission to Dr. Demeterio, that admission was made during a routine medical examination to determine whether he had a personality disorder. A copy of Dr. Demeter-io’s “psychiatric report” dated March 5, 1993 was attached to a Medical Examination Optional Form # 157 dated March 8, 1993. In Dr. Demeterio’s report, under the category of “HISTORY,” she related the history Pazcoguin had given her. There she reported:

Unlike his subsequent admission to Inspector Myers, which we discuss next, Pazeoguin’s admission of marijuana use made to Dr. Demeterio occurred during a routine medical examination. Dr. Deme-terio had no reason to suspect that Pazco-guin would admit to having used marijuana, and her examination was not conducted for the purpose of obtaining any such admission. This is far different from the circumstances in Matter of K , in which the alien confessed his criminal conduct during an interrogation by a police officer. Matter of K, 7 I & N Dec. at 595. We conclude that Pazcoguin’s admission to Dr. Demeterio is not rendered invalid due to Dr. Demeterio’s failure to provide him with a definition and the essential elements of the subject offense.

BIA precedent,. however, precludes consideration of Pazcoguin’s admission to Inspector Myers. That admission occurred during questioning by an INS inspector to determine, among other things, whether Pazcoguin was excludable as a result of his prior use of marijuana. Inspector Myers confronted Pazcoguin with his earlier admission to Dr. Demeter-io and asked him about it:

It is clear from the foregoing questioning that Inspector Myers was seeking answers from Pazcoguin which would implicate him in having committed the crime of possession or use of marijuana in the Phil *1218 ippines, and this information was being sought to determine his excludability from the United States. Inspector Myers was duty-bound to know and apply BIA rules in obtaining Pazcoguin’s admission, a duty which was not excused by Pazcoguin’s previous admission to Dr. Demeterio. See id. at 596-97 (holding that the immigration officer should have complied with the BIA’s procedural rules and provided the alien with the elements of the offense, even if the alien had made an earlier admission to a police officer). Because Inspector Myers failed to provide Pazcoguin with a definition and the essential elements of the crime of possession or use of marijuana under Philippine law, the BIA should not have considered Pazcoguin’s admission to Inspector Myers.

3. The admission must be voluntary.

Pazcoguin has made no showing that his admission to Dr. Demeterio was not voluntary, unequivocal, or unqualified, as required by Matter of L, 2 I & N Dec. 486 , 488, 1946 WL 6044 (BIA 1946).

We conclude that the INS satisfied its burden of production by presenting Pazcoguin’s admission to Dr. Demeterio. This was sufficient for the INS to carry its burden of producing “some evidence” that Pazcoguin was excludable. Matter of Walsh and Pollard, 20 I & N Dec. at 68 . Because Pazcoguin failed to rebut that showing, he failed to carry his ultimate burden of establishing that he was not inadmissible under any provision of the INA.

D. Pazcoguin’s Constitutional Challenges

Before we address Pazcoguin’s constitutional challenges, “it is important to underscore the limited scope of judicial inquiry into immigration legislation.” Fiallo v. Bell, 430 U.S. 787, 792 , 97 S.Ct. 1473 , 52 L.Ed.2d 50 (1977). “ ‘[T]he power over aliens is of a political character and therefore subject to only narrow judicial review.’ ” Id. (quoting Hampton v. Mow Sun Wong, 426 U.S. 88 , 101 n. 21, 96 S.Ct. 1895 , 48 L.Ed.2d 495 (1976)). Because of its broad power over immigration matters, “ ‘Congress regularly makes rules that would be unacceptable if applied to citizens.’ ” Id. (quoting Mathews v. Diaz, 426 U.S. 67, 80 , 96 S.Ct. 1883 , 48 L.Ed.2d 478 (1976)).

Pazcoguin contends that INA § 212(a)(2)(A)(i)(II) violates his right to procedural due process because it allows him to be excluded “based solely on his own statement” without any determination that he actually committed an offense. We are unpersuaded by this argument. As an alien in exclusion proceedings, Pazcoguin “has no procedural due process rights regarding his admission or exclusion.... “Whatever the procedure authorized by Congress is, it is due process as far as an alien denied entry is concerned.’ ” Barrera-Echavarria v. Rison, 44 F.3d 1441, 1449 (9th Cir.1995) (quoting Shaughnessy v. United States ex rel. Mezei, 345 U.S. 206, 212 , 73 S.Ct. 625 , 97 L.Ed. 956 (1953)) (quoting United States ex rel. Knauff v. Shaughnessy, 338 U.S. 537, 544 , 70 S.Ct. 309 , 94 L.Ed. 317 (1950)). The statute provides the only process Pazcoguin is due, and he received that process.

Pazcoguin also argues that INA § 212(a)(2)(A)(i)(II) is unconstitutional because it deprives his mother, a United States citizen, of a “substantial right ... to be re-united with her son.” This argument fails. “[D]espite the impact of ... [immigration] classifications on the interests of those already within our borders, congressional determinations such as this one are subject only to limited judicial review.” Fiallo, 430 U.S. at 795 n. 6, 97 S.Ct. 1473 . Pazcoguin falls within a classification of aliens whom Congress has seen *1219 fit to exclude. Despite the pain this may-cause his mother, we will not disturb that classification.

REVIEW DENIED.

. This case is governed by the transitional rules of IIRIRA. See Kalaw v. INS, 133 F.3d 1147, 1150 (9th Cir.1997).

. With regard to the INS’s second ground for Pazcoguin's exclusion, that he was an alien without a valid immigrant visa, INA § 212(a)(7)(A)(i)(I), the BIA held that the visa issued to him was invalid because his marijuana admission rendered him inadmissable at the time the visa was issued. Our analysis of both grounds for exclusion is the same. In both, we must determine whether Pazcoguin was excludable for having admitted conduct which constituted the essential elements of a controlled substance violation under Philippine law.

. In her dissent, Judge Berzon asserts that the INS conceded in its brief to this court that the "unless authorized by law" clause is an element of the crime. For this assertion, the dissent relies on part of a passage from a Philippine treatise that was quoted by the INS. In the very next paragraph of the material the INS quoted, however, the treatise states unequivocally that "[t]he phrase 'unless lawfully authorized’ ... states an element of defense and, therefore, it is not necessary to allege in the information that the accused is not authorized to possess” the controlled substance.