Merly Gallo appeals' her 92-month sentence for conspiring to possess with intent to distribute cocaine in violation of 21 U.S.C. § 846; The sole issue she raises on appeal concerns whether the district court properly enhanced her sentence two points for possession of a firearm by her co-conspirators under § 2Dl.l(bj(l) of the United States Sentencing Guidelines. Because we hold that a § 2Dl.l(b)(l) enhancement requires a factual finding of reasonable foreseeability, we vacate Defendant’s sentence, and remand to the district court to determine whether Gallo could reasonably foresee that her co-conspirators would possess firearms in furtherance of a jointly undertaken narcotics transaction.

I.

On April 29, 1997, Defendant Gallo and four co-conspirators (Blanco, Gordon, Diaz, and Gomez) pled .guilty to conspiring to possess cocaine with intent to distribute in violation of 21 U.S.C. § 846. Among other things, the evidence showed that Gallo participated in a narcotics transaction on November 7, 1996 at the apartment of her co-conspirator Gomez. At eleven-thirty that morning, Gallo and Diaz arrived at Gomez’s apartment. Two hours later, Blanco and Gordon arrived with sevén kilos of cocaine. Each man also came.armed with a pistol tucked in his waistband. An informant, Maria Nunez, then arrived at Gomez’s apartment and was let in by Gallo. Nunez inspected the cocaine in front of Gallo and her co-conspirators. Gallo then left with Nunez and was' súbsequently arrested. ; .

At her sentencing, on January 30, 1998, Gallo received a two-point sentence enhancement under U.S.S.G. § 2Dl.l(b)(l) based on the fact that two of her co-conspirators (Gordon and Blanco) possessed firearms during the course of the[*1280] narcotics conspiracy. In awarding the enhancement, the district court exclusively relied on commentary to § 2D1.1 which states:

The enhancement for weapon possession reflects the increased danger of violence when drug traffickers possess weapons. The adjustment should be applied if the weapon was present, unless it is dearly improbable that the weapon was connected with the offense.

U.S.S.G. § 2D1.1, comment, (n.3) (emphasis added). The district court did not consider the relevance of U.S.S.G. § lB1.3(a)(l)(b) which outlines the requirements for sentence enhancements based on co-conspirator conduct. Neither the United States nor the Defendant made any reference to the Guideline at Defendant’s sentencing colloquy. This provision unambiguously limits enhancements, “in the case of a jointly undertaken criminal activity ... [to] all reasonably foreseeable acts and omissions of others in furtherance of the jointly undertaken criminal activity.” Id. (emphasis added). However, the Defendant did argue that a “reasonable foreseeability” finding was required for § 2D1.1 enhancements for co-conspirator conduct, citing instead to United States v. Vold, 66 F.3d 915 (7th Cir.1995) (requiring a reasonable foreseeability finding, in conjunction with § lB1.3(a)(l)(b), for § 2Dl.l(b)(l) firearms possession enhancements based on co-conspirator conduct).

The United States countered that § 2Dl.l(b)(l) did not require reasonable foreseeability, and that, in any event, Gallo could reasonably have foreseen her co-conspirators’ firearms possession. The district court ordered the § 2D1.1(b)(1) enhancement finding only that it was not clearly improbable that the weapons possessed by Blanco and Gordon were connected with the offense, while refusing to make an alternative finding that the co-conspirators’ possession was or was not reasonably foreseeable. ^[1]

II.

We review the district court’s findings of fact under U.S.S.G. § 2Dl.l(b)(l) for clear error, and the application of the Sentencing Guidelines to those facts de novo. See United States v. [*1281] Hall, 46 F.3d 62, 63 (11th Cir.1995) (citing United States v. Herrera, 931 F.2d 761, 762 (11th Cir.1991)).

To begin, § 2Dl.l(b)(l) of the Sentencing Guidelines, which sets out specific offense characteristics pertaining to drug offenses, provides for a two-level increase in base offense level “[i]f a dangerous weapon (including a firearm) was possessed .... ” Id. The commentary to that section also provides that “[t]he adjustment should be applied if the weapon was present, unless it was clearly improbable that the weapon was connected with the offense.” U.S.S.G. 2D1.1, comment, (n.3). In this case, Gallo does not contest the district court’s application of note 3 of the commentary to 2D1.1. Indeed, it is plain from the record that the firearm was directly connected to the drug-trafficking offense. However, this does not end our inquiry. Gallo did not actually possess the firearms in question. Instead, the firearms were possessed by two of her co-conspirators.

U.S.S.G. § lB1.3(a)(l)(b) outlines the requirements for sentence enhancements based on co-conspirator conduct. The Guideline instructs that an act may be imputed from one co-conspirator to another provided the conduct was (1) “reasonably foreseeable,” and (2) “in furtherance of the jointly undertaken criminal activity....” Id. The Guidelines are promulgated by the United States Sentencing Commission, pursuant to the Sentencing Reform Act of 1984, as amended, § 18 U.S.C. 3551 et seq., 28 U.S.C. §§ 991-998, and have the binding force of a legislative enactment. See Williams v. United States, 503 U.S. 193, 200-01, 112 S.Ct. 1112, 117 L.Ed.2d 341 (1992). In addition, the commentary for § lB1.3(a)(l)(b) reads:

[I]n the case of a jointly undertaken criminal activity, subsection (a)(1)(B) provides that a defendant is accountable for the conduct (acts and omissions) of others that was both:

(i) in furtherance of the jointly undertaken criminal activity; and

ill) reasonably foreseeable in connection with that criminal activity.

Id. at comment, (n.2). (emphasis added). Guideline commentary “must be given ‘controlling weight unless it is plainly erroneous or inconsistent with the regulation’ ” it interprets or contrary to federal law. Stinson v. United States, 508 U.S. 36, 45, 113 S.Ct. 1913, 123 L.Ed.2d 598 (1993) (quoting Bowles v. Seminole Rock & Sand Co., 325 U.S. 410, 414, 65 S.Ct. 1215, 89 L.Ed. 1700 (1945)). In short, both § lB1.3(a)(l)(b) and its commentary unambiguously direct that sentence enhancements for co-conspirator conduct will be limited to those acts which are reasonably foreseeable.

Therefore, the central question squarely presented is whether a § 2D1.1(b)(1) firearms enhancement based on a co-conspirator’s firearms possession requires that the conduct be reasonably foreseeable by a defendant.

Our first foray into this issue occurred in United States v. Otero, 890 F.2d 366 (11th Cir.1989), a short per curiam opinion. There, we simply outlined a three-part test for § 2Dl.l(b)(l) sentence enhancements based on co-conspirator conduct:

Sentence enhancement for a co-conspirator’s firearms possession is proper if three conditions are met: first, the possessor must be charged as a co-conspirator; second, the co-conspirator must be found to have been possessing a firearm in furtherance of the conspiracy; and third, the defendant who is to receive the enhanced sentence must have been a member of the conspiracy at the time of the firearms possession.

Otero, 890 F.2d at 367. ^[2] The Otero test does not explicitly reference any requirement that the co-conspirator’s possession[*1282] be foreseeable to the defendant. However, in articulating this test, the Otero court cited to United States v. Missick, 875 F.2d 1294, 1301-02 (7th Cir.1989) and Pinkerton v. United States, 328 U.S. 640, 66 S.Ct. 1180, 90 L.Ed. 1489 (1946). Missick laid out a similar three-part test for § 2D1.1(b)(1), explaining that “Missick may still have been properly subject to an enhanced sentence based on the possession of firearms by Whisner and Fluhr without individually possessing a firearm under the theory of co-conspirator liability established in Pinkerton. ...” Missick, 875 F.2d at 1301. And in Pinkerton, the Supreme Court elucidated the classic theory of co-conspirator liability. Notably, the Pinkerton rationale discussed the same three elements established in Otero and Missick, see Pinkerton, 328 U.S. at 642-47, 66 S.Ct. 1180, but then plainly instructed that co-conspirator liability cannot be found “if the substantive offense committed ... was merely a part of the ramifications of the plan which could not be reasonably foreseen as a necessary or natural consequence of the unlawful agreement.” Pinkerton, 328 U.S. at 647-48, 66 S.Ct. 1180 (emphasis added).

At oral argument, the United States suggested that the Otero test does not require a reasonable foreseeability finding, even if the Defendant could establish that the co-conspirators’ conduct was not reasonably foreseeable to her. ^[3] Rather, the government argued, Otero requires only that the government prove by a preponderance of the evidence that the firearm possessor was a co-conspirator, that the possession was in furtherance of the conspiracy, and finally, that the Defendant was a member of the conspiracy at the time of possession. We disagree. We read Otero to be consonant with the traditional theory of co-conspirator liability requiring reasonable foreseeability, first outlined in Pinkerton and later promulgated in U.S.S.G. § lB1.3(a)(l)(b). Our conclusion is supported by the overwhelming authority of our caselaw which consistently has read Otero to require reasonable foreseeability.

We first revisited Otero in United States v. Martinez, 924 F.2d 209 (11th Cir.1991). There, we clarified that Otero “is fully in accord with the Guidelines and the commentary to § lB1.3(a)(l). Otero follows the Pinkerton rationale, which, like the Guidelines, requires that the firearm possession ‘be reasonably foreseen as a necessary or natural consequence of the unlawful agreement.’ ” Martinez, 924 F.2d at 210 n.1 (citing Pinkerton, 328 U.S. at 648, 66 S.Ct. 1180). Then in Freyre-Lazaro, in Pessefall, and again in Green, we applied the Otero test and specifically determined that the co-conspirator conduct was “reasonably foreseeable” despite defendants’ claims that they lacked actual knowledge of the possession. United States v. Freyre-Lazaro, 3 F.3d 1496, 1506 (11th Cir.1993); United States v. Pessefall, 27 F.3d 511, 514-15 (11th Cir.1994); United States v. Given, 40 F.3d 1167, 1175 (11th Cir.1994). Later, in Aduwo, we noted that a defendant may be awarded a firearms possession enhancement for co-conspirator conduct under Otero because of the “basic [.Pinkerton ] rule that conspirators are liable for the reasonably foreseeable acts of their co-conspirators in furtherance of the conspiracy.” United States v. Aduwo, 64 F.3d 626, 629 (11th Cir.1995). We reiterated this proposition in United States v. Luiz, 102 F.3d 466, 468 (11th Cir.1996) (stating that the “rationale [under Otero ] for attributing the possession of a firearm by one co-conspirator to another is the Pinkerton rule that ‘conspirators are liable for the reasonably foreseeable acts of their co-conspirators in furtherance of the conspiracy’ ”) (citing Aduwo, 64 F.3d at 629). Finally, in Aired, we explained that while “[a]ctual knowledge of the coconspirator’s firearm possession by the convicted defendant is not required [under Otero ] ..., possession must be reasonably foreseeable.” United States v. Alred, 144 F.3d 1405, 1420 (11th Cir.1998).

[*1283] However, our research also reveals that several cases have applied the Otero test without any discussion of reasonable foreseeability. See United States v. Matthews, 168 F.3d 1234, 1248 (11th Cir.1999); United States v. Delgado, 56 F.3d 1357, 1372 (11th Cir.1995); United States v. Reid, 69 F.3d 1109, 1115 (11th Cir.1995); United States v. Stanley, 24 F.3d 1314, 1322-23 (11th Cir.1994); United States v. Gates, 967 F.2d 497, 500 (1992). As best we can tell, only one of these cases, Gates, involved a defendant who made a state of mind defense to his § 2Dl.l(b)(l) firearms enhancement. See id., 967 F.2d 497, 500 (1992). In Gates, the defendant argued he lacked actual knowledge of his co-conspirators’ gun possession, and we concluded that the Otero test nevertheless was met. See id. at 500. The gun at issue was lodged under a driver’s car seat in close proximity to Gates who was sitting in a rear passenger seat. The issue of foreseeability was not-argued by Gates directly, and the facts suggest that the possession was reasonably foreseeable. See id. at 499. In the remaining four cases, the issue of reasonable foreseeability was not germane to the Otero analysis because the defendants did not contest their knowledge of the co-conspirator conduct. None of these cases hold or suggest in dicta that a reasonable foreseeability finding is irrelevant under Otero.

But even if there is doubt that Otero requires a reasonable foreseeability finding, it would not affect our conclusion today. Notably, when Otero was decided, the reasonable foreseeability requirement appeared in note one of the commentary to U.S.S.G. § 1B1.3 but not in the direct text of the Guideline itself. See U.S.S.G. § 1B1.3, comment. (n.1) (1989) (amended 1994). At the time Otero was decided, the Guidelines’ commentary was considered precatory, not mandatory, in our circuit and in the other federal circuits. See United States v. Stinson, 957 F.2d 813, 813 (11th Cir.1992) (per curiam) (interpreting the Guidelines’ commentary as non-binding); United States v. Johnson, 964 F.2d 124, 127 (2d Cir.1992) (finding the Guidelines’ policy statements to have less authority than the Guidelines themselves); United States v. Blackston, 940 F.2d 877, 893 (3d. Cir.1991) (stating that the Guidelines’ policy statements are merely “advisory”); United States v. Anderson, 942 F.2d 606, 609-14 (9th Cir.1991) (en banc) (treating the Guidelines’ commentary as something more than legislative history but something less than the Guidelines’ text).

In 1993, however, the Supreme Court overruled Stinson and determined that the Guidelines’ commentary was binding unless it was contrary to federal law or “plainly erroneous” in light of the Guidelines themselves. Stinson, 508 U.S. at 37, 44-45, 113 S.Ct. 1913. Stinson therefore effectively required sentencing courts to apply the “reasonable foreseeability” commentary to § lB1.3(a)(l)(b) when awarding an enhancement based on co-conspirator conduct. Moreover, in 1994, the Sentencing Commission expressly amended the Guidelines to include the reasonable foreseeability requirement directly in § lB1.3(a)(l)(b). Compare U.S.S.G. § 1B1.3 (1989) with U.S.S.G. § lB1.3(a)(l)(b) (1994). ^[4] This amend[*1284] ment, effective in November 1994, gave the reasonable foreseeability requirement of § lB1.3(a)(l)(b) the binding force of a legislative enactment. See Williams, 503 U.S. at 200-01, 112 S.Ct. 1112.

We conclude that each of these legal developments constitutes sufficient change in the legal and statutory landscape to undermine any suggestion in Otero that reasonable foreseeability is not required by U.S.S.G. § 2Dl.l(b)(l). As a rule, our prior precedent is no longer binding once it has been substantially undermined or overruled by either a change in statutory law or Supreme Court jurisprudence or if it is in conflict with existing Supreme Court precedent. See United States v. Romeo, 122 F.3d 941, 942 n. 1 (11th Cir.1997) (determining that prior precedent does not have to be followed by a panel where a “change in statutory law” undermines the precedent) (citing United States v. Woodard, 938 F.2d 1255, 1258 n. 4 (11th Cir.1991)) ^[5] ; Lufkin v. McCallum, 956 F.2d 1104, 1107 (11th Cir.1992) (declining to follow prior panel holding “in order to give full effect to an intervening decision of the Supreme Court”) (citing United States v. Machado, 804 F.2d 1537, 1543 (11th Cir.1986)); Tucker v. Phyfer, 819 F.2d 1030, 1035 n. 7 (11th Cir.1987) (declining to follow prior panel opinion that failed to consider controlling Supreme Court precedent). Thus, even if we were to read Otero, as the government suggests, as eviscerating a reasonable foreseeability requirement for U.S.S.G. § 2D1.1(b)(1), that holding would be in square conflict with both the Supreme Court’s decision in Stin-son and the plain language of U.S.S.G. § lB1.3(a)(l)(b) subsequently adopted by the Sentencing Commission.

For these reasons, we hold that for a § 2Dl.l(b)(l) firearms enhancement for co-conspirator possession to be applied to a convicted defendant, the government must prove by a preponderance of the evidence: (1) the possessor of the firearm was a co-conspirator, (2) the possession was in furtherance of the conspiracy, (3) the defendant was a member of the conspiracy at the time of possession, and (4) the co-conspirator possession was reasonably foreseeable by the defendant. ^[6] We therefore vacate Defendant’s sentence and remand the proceedings to the district court to make a finding regarding the foreseeability of the co-defendants’ possession of the firearms, and impose sentence accordingly.

VACATED AND REMANDED.