OPINION
CANBY, Circuit Judge:Hernán Ismael Delgado petitions for review of a decision of the Board of Immigration Appeals (“BIA”) ordering him removed to his native El Salvador. The BIA denied Delgado’s applications for asylum, withholding of removal, and withholding under the Convention Against Torture (“CAT withholding”), finding that Delgado’s three prior offenses of driving under the influence (“DUI”), which were not aggravated felonies, constituted “particularly serious crimes” that made him ineligible for those forms of relief.1 The BIA also found Delgado ineligible for deferral of removal under the Convention Against Torture (“CAT deferral”) because he failed to demonstrate the requisite likelihood of future torture.
We dismiss in part and deny in part Delgado’s petition for review. We defer to the BIA’s view that, for purposes of withholding of removal, the applicable statute permits the Attorney General to decide by adjudication that an alien’s individual crime is “particularly serious” even though that crime is not classified as an aggravated felony. We also conclude that, for purposes of asylum, the Attorney General may determine by adjudication that a crime is “particularly serious” without first so classifying it by regulation. We further determine that we are without jurisdiction *1019to review the merits of such decisions. Finally, we hold that substantial evidence supports the decision of the BIA that Delgado failed to meet his burden of proving that he is more likely than not to be tortured if returned to El Salvador.
Background
Delgado, a native and citizen of El Salvador, entered the United States on a non-immigrant visitor visa over twenty years ago. In July 2001, the Immigration and Naturalization Service (“INS”)2 initiated removal proceedings against him because he had overstayed his visa. Delgado conceded removability but sought asylum, withholding of removal, CAT withholding and deferral, cancellation of removal under the Nicaraguan Adjustment and Central American Relief Act (“NACARA”), and suspension of deportation.
The Immigration Judge (“IJ”) denied Delgado’s request for CAT deferral, finding that Delgado had failed to show that he was more likely than not to be tortured if removed to El Salvador. The IJ also found that each of Delgado’s three prior felony DUI convictions constituted a “particularly serious crime” that barred him from eligibility for asylum under 8 U.S.C. § 1158(b) (2) (A) (ii), withholding of removal under 8 U.S.C. § 1231(b)(3)(B)(ii), and CAT withholding under 8 C.F.R. § 1208.16(d)(2).3 The BIA affirmed the decision of the IJ in an unpublished per curiam decision signed by one member, and this appeal followed.
Discussion
The BIA did not specify whether it reviewed de novo the IJ’s decision, but stated that it agreed with the IJ on the basis of “the record before [it].” The BIA’s simple statement of a conclusion, without analysis, suggests that it relied significantly on the IJ’s decision. In such situations, we review the decision of the BIA and look to the IJ’s oral decision “as a guide to what lay behind the BIA’s conclusion.” See Avetova-Elisseva v. INS, 213 F.3d 1192, 1197 (9th Cir.2000).
I. The “particularly serious crime” bar
The ultimate issue raised by Delgado is whether the BIA erred in deciding that his DUI convictions constituted “particularly serious crimes” that made him ineligible for withholding of removal and asylum. A major threshold question is whether the applicable statutes permit the agency to determine Delgado’s offenses to be “particularly serious” by individual adjudication not limited by certain statutory or regulatory requirements. We have jurisdiction under 8 U.S.C. § 1252(a)(2)(D) to review this question of law. Afridi v. Gonzales, 442 F.3d 1212, 1218 (9th Cir.2006).
Although this issue of the BIA’s authority to determine by adjudication that an alien’s crime is “particularly serious” arises with regard to both withholding of removal and asylum, the statutory context differs for each form of relief and raises distinctive legal subissues. We therefore treat the two forms of relief separately.
A. Withholding of Removal
An alien is ineligible for withholding of removal if, among other things, “the Attorney General decides that ... the alien, *1020having been convicted by a final judgment of a particularly serious crime, is a danger to the community of the United States.”4 8 U.S.C. § 1231(b)(3)(B). For the purposes of this provision,
an alien who has been convicted of an aggravated felony (or felonies) for which the alien has been sentenced to an aggregate term of imprisonment of at least 5 years shall be considered to have committed a particularly serious crime. The previous sentence shall not preclude the Attorney General from determining that, notwithstanding the length of sentence imposed, an alien has been convicted of a particularly serious crime.
Id. The question that naturally arises from this plain text is whether the last sentence is meant to limit the Attorney General (or his delegate, the BIA) to the universe of aggravated felonies described in the preceding sentence or, conversely, whether the last sentence simply preserves the Attorney General’s authority to determine a crime to be particularly serious regardless of the penalty or its designation or non-designation as an aggravated felony.
At the time the present appeal was argued, the BIA had not addressed this issue in a precedential opinion, in this case or any other. An unpublished decision by a single BIA member is not entitled to the deference prescribed by Chevron U.S.A., Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837, 842-43, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984). Garcia-Quintero v. Gonzales, 455 F.3d 1006, 1012-14 (9th Cir.2006). Recently, however, a three-member panel of the BIA has issued an extensive published opinion holding that § 1231(b)(3)(B) permits the Attorney General to decide by case-by-case adjudication that particular crimes are “particularly serious” even though they are not aggravated felonies. In re N-A-M-, 24 I & N Dec. 336, 338-39 (BIA 2007). Such a prec-edential opinion is entitled to Chevron deference. See Garcia-Quintero, 455 F.3d at 1012. For reasons that we now set forth, we conclude that the BIA’s interpretation of § 1231(b)(3)(B) is reasonable, and we accordingly defer to it.5
Two other circuits, which addressed the issue before the BIA weighed in with a precedential opinion, reached opposite results. The Third Circuit, applying a textual and structural approach, concluded that an offense “must be an aggravated felony to be ‘particularly serious.’ ” Alaka v. Attorney General of the United States, 456 F.3d 88, 104-05 (3d Cir.2006), cert. dismissed, 128 S.Ct. 828 (2007). The court reasoned that the sentence allowing the Attorney General to determine that a crime is particularly serious “notwithstanding the length of sentence imposed,” 8 U.S.C. § 1231(b)(3)(B), “explicitly refers back to the ‘previous sentence,’ and accordingly implies that [the Attorney General’s authority] is limited to aggravated felonies.” Id. The Seventh Circuit disagreed, concluding that “the absence of a ... provision for nonaggravated-felony *1021crimes does not imply that only aggravated felonies can qualify as ‘particularly serious’ crimes.” Ali v. Achim, 468 F.3d 462, 470 (7th Cir.2006), cert. dism., — U.S. -, 128 S.Ct. 828, 169 L.Ed.2d 624 (2007).
The BIA found persuasive the Seventh Circuit’s view that the designation of certain aggravated felonies as per se “particularly serious” does not preclude the Attorney General from deciding, on a case-by-case basis, that any other crime is also “particularly serious.” The BIA’s adoption of this position was reasonable. The statute does not limit the definition of “particularly serious” crimes to aggravated felonies. Nor does it expressly require the Attorney General, when considering whether a crime that is not categorically barred is “particularly serious,” to consider only aggravated felonies where the sentence imposed was less than five years.
The legislative history of the particularly serious crime bar, referred to by the BIA in In re N-A-M- 24 I. & N. Dec. at 339-340, supports this interpretation. In 1980, § 243(h) of the Immigration and Nationality Act was amended to deny withholding to an individual who “having been convicted by a final judgment of a particularly serious crime, constitutes a danger to the community of the United States.” Pub L. No. 96-212, § 202, 94 Stat. 102 (1980). Under this provision, the BIA determined on a ease-by-case basis which crimes were particularly serious, applying the balancing test of Matter of Frentescu, 18 I. & N. Dec. 244 (BIA 1982).6 This test did not take into account whether the crime in issue had been statutorily defined as an “aggravated felony.” In time, the BIA denominated some crimes as inherently particularly serious, so that individual determinations with regard to those crimes did not have to be undertaken. See, e.g., Matter of Garcia-Garrocho, 19 I. & N. Dec. 423, 425 (BIA 1986).
The statutory provision barring those convicted of “particularly serious” crimes from eligibility for withholding of removal then was amended three times. The Immigration Act of 1990 (the “1990 Act”) added the following language to § 243(h): “an alien who has been convicted of an aggravated felony shall be considered to have committed a particularly serious crime.” Pub.L. No. 101-649, 104 Stat. 4978, 5053. Nothing in the text or history of the 1990 Act suggests that Congress intended, by making aggravated felonies per se “particularly serious crimes,” to divest the Attorney General of his authority to determine, on a case-by-case basis, that other crimes were “particularly serious,” depending on the circumstances of their commission, among other things. And, notwithstanding the 1990 Act, the agency understood that it could adjudicate a crime to be “particularly serious” on a case-by-case basis. See Ahmetovic v. INS, 62 F.3d 48, 52 (2d Cir.1995) (agreeing with BIA’s conclusion that a crime need not be an aggravated felony to be adjudicated “particularly serious”); Matter of B-, 20 I. & N. Dec. 427, 430-31 (BIA 1991) (applying Frentescu factors under the 1990 Act to determine that the alien had been convicted of a particularly serious crime).7
*1022Congress relaxed the per se category-created by the 1990 Act in 1996 with the passage of section 413(f) of the Antiterrorism and Effective Death Penalty Act of 1996, Pub.L. No. 104-132, 110 Stat. 1214, 1269 (1996) (“AEDPA”). The AEDPA amended § 243(h) to allow the Attorney General, “in [his] discretion,” to override the categorical bar designating all aggravated felonies “particularly serious” when “necessary to ensure compliance with the 1967 United Nations Protocol Relating to the Status of Refugees.” Id.8 The categorical bar was again relaxed later that year with the passage of the Illegal Immigration Reform and Immigrant Responsibility Act of 1996, Division C of Pub.L. No. 104-208, 110 Stat. 3009-546, 3009-602 (“IIRI-RA”). IIRIRA enacted the provision at issue here, which limits application of the categorical bar to aggravated felons sentenced to 5 years’ or more imprisonment. Id.
We recognize that one of the aims of Congress in enacting the post-1990 statutory amendments was probably to avoid sweeping minor crimes into the categorical aggravated felony bar. But nothing in the legislative history indicates that Congress intended, by creating a categorical bar and by later relaxing that categorical bar, to eliminate the Attorney General’s pre-exist-ing discretion to determine that, under the circumstances presented by an individual case, a crime was “particularly serious,” whether or not the crime was an aggravated felony. We therefore find the BIA’s interpretation of the statute reasonable, and conclude that the BIA was entitled to determine, by adjudication, that Delgado’s DUI convictions were particularly serious crimes that barred him from eligibility for withholding of removal under 8 U.S.C. § 1231(b)(3)(B) and CAT withholding under 8 C.F.R. § 1208.16(d)(2).
B. Asylum
We now turn to whether the BIA was authorized to determine that Delgado’s crimes were “particularly serious” for the purposes of his asylum application.9 Just as in the context of withholding, the relevant statute provides that an alien is ineligible for asylum if the Attorney General determines that “the alien, having been convicted of a particularly serious crime, constitutes a danger to the community.” 8 U.S.C. § 1158(b)(2)(A)(ii). For the purposes of this provision, “an alien who has been convicted by a final judgment of an aggravated felony shall be considered to have been convicted of a particularly serious crime.” 8 U.S.C. § 1158(b)(2)(B)©. In addition, “[t]he Attorney General may designate by regulation offenses that will be considered to be a [particularly serious] crime....” 8 U.S.C. § 1158(b)(2)(B)(ii).
*1023There seems little question that this last provision permits the Attorney General to make particular crimes categorically “particularly serious” even though they are not aggravated felonies. The provision would be wholly redundant if the Attorney General were confined to making only aggravated felonies “particularly serious” crimes by regulation. The different question posed by this asylum statute is whether the Attorney General can determine by adjudication that an individual alien’s crime was “particularly serious,” or whether he must first by regulation provide that the particular crime is to be so characterized.
Our discussion of the withholding statute is instructive. Just as with withholding, the agency initially made the determination whether an alien’s crime was particularly serious strictly by adjudication, applying the Frentescu factors. See Frentescu, 18 I. & N. Dec. at 247. Congress intervened in the 1990 Act only to ensure that certain crimes (aggravated felonies) would be categorically determined to be “particularly serious,” regardless of the circumstances of their commission.10 Congress then added its permission for the Attorney General in asylum cases to “designate by regulation offenses that will be considered to be [particularly serious crimes].” Id. It is most reasonable to interpret this provision as similarly concerned with the categorical designation of additional crimes as “particularly serious.” Indeed, it would be difficult to designate by regulation crimes that “will be considered” to be particularly serious unless the designation is categorical for those crimes. The provision simply does not speak to the ability of the Attorney General to determine in an individual case that the circumstances of an alien’s commission of a crime made that crime particularly serious, even though the same offense committed by other persons in other circumstances would not necessarily be particularly serious. The statute does not require the Attorney General to anticipate his adjudication by a regulation covering each particular crime. See Ali, 468 F.3d at 469.
We therefore conclude that the BIA did not err in proceeding to determine by adjudication, in the absence of regulation, whether Delgado had committed a “particularly serious” crime that rendered him ineligible for asylum.
C. The merits of the BIA’s decision
The next question for decision is whether we may review the merits of the BIA’s determination that Delgado’s DUI convictions were “particularly serious crimes.” We conclude that we may not.11
We are statutorily precluded from reviewing decisions of the Attorney General “the authority for which is specified under this subchapter to be in the discretion of the Attorney General ..., other than the granting of relief under section 1158(a) of this title [relating to asylum].”12 8 U.S.C. *1024§ 1252(a)(2)(B)(ii). In Matsuk v. INS, 247 F.3d 999 (9th Cir.2001), we were presented with a determination by the BIA that an aggravated felony resulting in a sentence of less than five years imprisonment was a “particularly serious” crime. We held that the BIA’s ruling was an unreviewable discretionary decision within the meaning of the statutory bar. See id. at 1002. In later explaining this ruling, we stated:
[T]he decision at issue in Matsuk— whether to classify an alien’s past offense as a ‘particularly serious crime’ under § 1231(b)(3)(B) — is a decision that is entirely lacking in statutory guidelines. Under the language of the statute, this decision is left entirely to the discretion of the Attorney General, with no governing statutory standards.
Spencer Enters., Inc. v. United States, 345 F.3d 683, 690 (9th Cir.2003). The language that Matsuk and Spencer found to “specify” the authority to be discretionary in the Attorney General, within the meaning of § 1252(a)(2)(B)(ii), was the statutory provision denying withholding “if the Attorney General decides that ... an alien has been convicted of a particularly serious crime.” 8 U.S.C. § 1231(b)(3)(B); see also Spencer, 345 F.3d at 689-90. Virtually identical statutory language relates to asylum. Asylum is barred “if the Attorney General determines that ... the alien, ha[s] been convicted ... of a particularly serious crime.”13 8 U.S.C. § 1158(b)(2)(A)(ii). The statutory language, therefore, suggests that the ultimate decision whether a crime is “particularly serious” is a discretionary decision not subject to our review with regard both to withholding of removal and of asylum.
After the decisions in Matsuk and Spencer, Congress enacted the REAL ID Act of 2005, which provides that nothing in the provision limiting review of the Attorney General’s discretionary decisions “shall be construed as precluding review of constitutional claims or questions of law raised upon a petition for review.” 8 U.S.C. § 1252(a)(2)(D). Our decisions subsequent to the REAL ID Act make clear, however, that the ultimate determination by the Attorney General that a crime is “particularly serious” is still an unreviewable discretionary decision. We so stated in Unuakhaulu v. Gonzales, 416 F.3d 931, 935 (9th Cir.2005). Then, in Afridi v. Gonzales, 442 F.3d 1212 (9th Cir.2006), we were presented with a case where the IJ had failed to engage in a case-specific application of the Frentescu factors. Id. at 1219. We determined that this failure raised a point of law, and we remanded for further proceedings. Id. at 1219-21. In doing so, however, we recognized the limits of the question of law that we were deciding: “While we cannot reweigh evidence to determine if the crime was indeed particularly serious, we can determine whether the BIA applied the correct legal standard in making its determination.” Id. at 1218. A fair reading of Afridi is that the ultimate determination of the “particularly serious” nature of a crime is not subject to our review.
Most recently, we decided in Ramadan v. Gonzales, 479 F.3d 646 (9th Cir.2007), that in preserving our authority to review questions of law, the REAL ID Act permitted us to review mixed questions of law and fact. Id. at 654. Ramadan made clear, however, that the REAL ID Act did not “restore [our] jurisdiction over discre*1025tionary determinations.” Id. And it gave as an example of a statutorily-specified discretionary determination the “Attorney General’s determination ... that an aggravated felony is a particularly serious crime,” citing Matsuk. Id. at 655. It seems clear under our precedent, therefore, that the authority to review questions of law or mixed questions of law and fact under the REAL ID Act did not include a power to review a determination of the Attorney General that a crime was “particularly serious.”
The dissent reads Morales v. Gonzales, 478 F.3d 972 (9th Cir.2007), to hold that we have jurisdiction over the “particularly serious” question as it relates to asylum applications. We do not read Morales to hold as much. To be sure, there is language in that case suggesting that the court had jurisdiction over the “particularly serious” question because it fell under an exception to the jurisdiction-stripping statute. Morales, 478 F.3d at 980 (“The denial of asylum is renewable because it is specifically exempted from § 1252(a)(2)(B)(ii)’s jurisdiction-stripping provisions.”). The court, however, did not review the merits of the “particularly serious” finding. Instead, it determined whether the immigration judge relied on the wrong facts in concluding that the crime was particularly serious — a question of law that is reviewable. Morales, 478 F.3d at 981-83; see Afridi, 442 F.3d at 1218.
Moreover, § 1252(a)(2)(B)(ii) excepts from the jurisdictional bar the granting of relief under § 1158(a), relating to the authority to apply for asylum; it does not speak to § 1158(b), which is the “particularly serious” provision. It is true that the interrelation between §§ 1158(a) and (b) means that the success of an asylum application may depend on whether there has been a “particularly serious” crime. That alone, however, does not overcome the obvious problem that § 1252 excepts only § 1158(a). Thus, neither the statutory framework nor Morales supports the dissent’s theory that § 1252 excepts all asylum-related decisions from its jurisdictional bar.
Finally, in Morales we suggested that, because our past decisions had held the Attorney General’s determination of a “particularly serious” crime to be an unre-viewable discretionary determination only with regard to aggravated felonies, it would be an extension of our law to apply the same rule to other crimes. See 478 F.3d at 979-80. Morales found it unnecessary to decide whether such an extension was appropriate, but our analysis above should make it clear that, under our precedent, the Attorney General’s unreviewable discretion must extend to both aggravated felonies and other crimes, and to both withholding of removal and asylum. The statutory framework for all of these decisions is virtually identical. The Attorney General exercises the same specified discretionary authority, and applies the same statutory language that bars relief, in all of these instances. There is, in our view, no analytically sound way to draw a line permitting review of some of these determinations and excluding review of others.
We conclude, therefore that we are precluded by § 1252(a)(B)(ii) from reviewing the merits of the BIA’s determination that Delgado’s crimes were “particularly serious.” That issue does not present a reviewable question of law within the meaning of the REAL ID Act, 8 U.S.C. § 1252(a)(2)(D).
II. Relief under the Convention Against Torture
We have jurisdiction pursuant to 8 U.S.C. § 1252(a) to review the BIA’s denial of Delgado’s claim for CAT deferral, see Morales, 478 F.3d at 980-81, and we re*1026view that decision for substantial evidence. Bellout v. Ashcroft, 363 F.3d 975, 979 (9th Cir.2004). In order to be eligible for CAT deferral, Delgado must prove that he is more likely than not to be tortured upon his return to El Salvador. Id.; 8 C.F.R. § 1208.17(a).
As the IJ noted, Delgado presented evidence that his mother, and probably his father, were victims of the rampant human rights violations that took place in El Salvador in the late 1970s and early 1980s. However, Delgado has not provided sufficient evidence that he currently risks being harmed if he returns to his native country. Country reports indicate that conditions in El Salvador have improved significantly since Delgado left the country, and that there is no longer evidence of politically motivated violence, killings, or disappearances in El Salvador. We therefore conclude that the BIA’s decision that Delgado is not entitled to CAT deferral is supported by substantial evidence.
Conclusion
The petition for review is DISMISSED in part and DENIED in part.
. All three convictions were for felony DUI. One involved an injury accident, and two resulted in prison terms of less than five years.
. Effective March 1, 2003, the functions of the INS were transferred to the Department of Homeland Security. See Homeland Security Act of 2002, Pub.L. No. 107-296, 116 Stat. 2135 (Nov. 25, 2002). This transfer has no effect on the review of Delgado’s case.
. The IJ also denied Delgado's applications for suspension of deportation and relief under NACARA. Delgado does not seek review of those denials.
. We have upheld the BIA's interpretation of this statute to require "only the factual finding of conviction of a particularly serious crime to support the determination of danger to the community,” without the necessity of a separate finding of such danger. Ramirez-Ramos v. INS, 814 F.2d 1394, 1397 (9th Cir.1987). We therefore confine our analysis here to the question of "particularly serious” crimes, and omit any separate consideration of danger to the community.
. In Morales v. Gonzales, we assumed without analysis that the Attorney General could deem a non-aggravated felony "particularly serious.” 478 F.3d 972, 980-81, 983 (9th Cir.2007). There, we remanded to the BIA for a redetermination, based on the correct legal standard, of whether Morales’s non-aggravated felony constituted a "particularly serious crime.” Id. at 983. Because the statutory interpretation of § 1231(b)(3)(B) is squarely contested here, we address the issue in depth for the first time.
. The BIA looked "to such factors as the nature of the conviction, the circumstances and underlying facts of the conviction, the type of sentence imposed, and, most importantly, whether the type and circumstances of the crime indicate that the alien will be a danger to the community.” Frentescu, 18 I. & N. Dec. at 247.
. The long history of case-by-case determination of "particularly serious” crimes bears more weight, in our view, than the canons of construction relied upon by the dissent. Canons of statutory construction "are tools designed to help courts better determine what Congress intended, not to lead courts to interpret the law contrary to that intent.” Scheidler v. Nat'l Org. for Women, 547 U.S. 9, 23, *1022126 S.Ct. 1264, 164 L.Ed.2d 10 (2006). See also Chickasaw Nation v. United States, 534 U.S. 84, 93-95, 122 S.Ct. 528, 151 L.Ed.2d 474 (2001).
. Although the legislative history is sparse, there seems to be no doubt that one purpose of this enactment was to prevent violations of the Refugee Convention’s non-refoulement provision .that might occur because of a rigid application of the aggravated felony bar. See In re Q-T-M-T-, 21 I. & N. Dec. 639, 648 n. 4 (BIA 1996). Such treaty violations were becoming more likely because, at the time, the list of aggravated felonies was expanding, and a categorical bar could have included "fairly minor offenses” in its sweep. Id. (internal quotations and citation omitted); see also Choeum v. INS, 129 F.3d 29, 42-44 (1st Cir.1997) (accepting INS’s argument that 1996 amendments were fueled by expansion of the term “aggravated felony”).
. The BIA's precedential decision in In re NA-M- did not address § 1158(b)(2)(B)(I) because the asylum application in that case was untimely. We therefore have no precedential decision of the BIA to be accorded Chevron deference on the precise asylum question presented here.
. As we described in the previous section, Congress relaxed its categorical bar somewhat with regard to withholding of removal. It did not do so with regard to asylum.
. Other circuits have split on this issue. The Seventh Circuit holds that it is without jurisdiction to review the merits of the determination of an alien’s crime to have been "particularly serious,” see Ali, 468 F.3d at 468; Tunis v. Gonzales, 447 F.3d 547, 549 (7th Cir.2006), but the Third Circuit took a contrary position in Alaka, 456 F.3d at 94-101, as did the Second Circuit in Nethagani v. Mukasey, 532 F.3d 150, 154 (2d Cir.2008).
.The preservation of our authority to review discretionary decisions relating to asylum is confined to decisions under § 1158(a), which does not include the bar for "particularly serious” crimes. We have described this provision authorizing review of an otherwise-unreviewable discretionary decision as relating to "the ultimate authority whether to grant asylum.” See Spencer Enters., Inc. v. United States, 345 F.3d 683, 690 (9th Cir. *10242003). Thus, not every ruling arising in an asylum case is subject to review. See, e.g., Lanza v. Ashcroft, 389 F.3d 917, 924 (9th Cir.2004).
. In Ramadan v. Gonzales, 479 F.3d 646 (9th Cir.2007), discussed later in this opinion, we emphasized the statutory language "if the Attorney General decides that” as granting un-reviewable discretion. Id. at 655.