Defendant-Appellant Frank Jackson appeals from an amended judgment entered August 23,1994 in the United States District Court for the Southern District of New York, Morris E. Lasker, Judge, on remand from this court for resentencing, see United States v. Jackson, 968 F.2d 158 (2d Cir.), cert. denied, — U.S. -, 113 S.Ct. 664, 121 L.Ed.2d 589 (1992) (“Jackson F), following Jackson’s plea of guilty to one count of possessing with intent to distribute approximately 300- grams of a mixture or substance containing cocaine base in violation of 21 U.S.C. §§ 812, 841(a)(1), and 841(b)(1)(A), and 18 U.S.C. § 2. On remand, Jackson was sentenced principally to the minimum ten-year term of imprisonment mandated by § 841(b)(1)(A) for persons convicted of possessing with intent to distribute certain mixtures or substances containing fifty grams or more of cocaine base. See United States v. Jackson, 856 F.Supp. 176 (S.D.N.Y.1994) (“Jackson II ”). For the reasons that follow, we affirm the amended judgment of the district court.
Jackson contends on appeal that the district court erred in imposing the ten-year sentence because: (1) the substance that Jackson possessed was not crack,, and only *1422crack is a “mixture or substance ... which contains cocaine base” within the meaning of § 841(b)(1)(A)(iii); (2) the enhanced penalties imposed by § 841(b)(1)1 upon persons who commit drug offenses involving cocaine base violate the equal protection guarantee of the Fifth Amendment; and (3) the imposition of the ten-year mandatory minimum sentence in this ease violates the Eighth Amendment prohibition against cruel and unusual punishments. We address these contentions in turn.
On the prior appeal in this case, reversing a district court determination that § 841(b)(1)(A)(iii) was unconstitutionally vague, see United States v. Jackson, 768 F.Supp. 97 (S.D.N.Y.1991), we ruled that “a-substance that has been identified as ‘cocaine base’ by chemists but that may not be pure enough to be used as ‘crack’ falls within the meaning of ‘cocaine base’ under 21 U.S.C. § 841 and Guidelines § 2D1.1.” Jackson I, 968 F.2d at 161. On remand, the district court determined that the substance which Jackson had possessed was cocaine base, but not crack, see Jackson II, 856 F.Supp. at 179-80, and imposed the mandatory ten-year sentence required by the statute as previously construed in Jackson I. See Jackson II, 856 F.Supp. at 181. Jackson urges on this appeal that we revisit the issue, pointing out that the United States Sentencing Commission (the “Commission”) has amended the notes following the Drug Quantity Table that constitutes USSG § 2Dl.l(c) by defining cocaine base as meaning -only “crack,” in express disagreement with this circuit’s definition of cocaine base in Jackson I. See USSG App. C., amendment 487, effective November 1, 1993.
This court has explicitly rejected this view. In United States v. Palacio, 4 F.3d 150 (2d Cir.1993), cert. denied, — U.S. -, 114 S.Ct. 1194, 127 L.Ed.2d 543 (1994), we held that:
Although the Commission’s interpretation of section 2D1.1 in the amended commentary will be authoritative with respect to the Guidelines, the amendment cannot revise the statutory interpretation we have already made in Jackson. Even if the Commission’s pending view of the term “cocaine base” in the Guidelines might have influenced us to adopt a congruent interpretation of the statutory term as an original matter, once we have construed the statute, we will not reinterpret it in the absence of new guidance from Congress. See Lechmere, Inc. v. NLRB, 502 U.S. 527, 535-38, 112 S.Ct. 841, 847-48, 117 L.Ed.2d 79 (1992); Maislin Industries, U.S., Inc. v. Primary Steel, Inc., 497 U.S. 116, 130-31, 110 S.Ct. 2759, 2768, 111 L.Ed.2d 94 (1990).
4 F.3d at 154 (emphasis added).
Jackson attempts to distinguish Palacio on the basis that it was decided on August 31, 1993, prior to the effective date (November 1, 1993) of amendment 487. He contends that by allowing amendment 487 to go into effect without modification or disapproval pursuant to 28 U.S.C. § 994(p),2 Congress provided the “new guidance” that was contemplated by Palacio, 4 F.3d at 154, but was unavailable when that ease was decided.
*1423However, Palacio clearly addressed the prospective effect of amendment 487, which had been proposed by the Commission and was pending before Congress when Palacio was decided, pointing out that the amendment “will be authoritative with respect to the Guidelines ... [but] cannot revise the statutory interpretation we have already made in Jackson.” 4 F.3d at 154 (emphasis added). Palacio further addressed that effect in assessing the future interplay between the Guidelines and the underlying sentencing statute with respect to cocaine base prosecutions, stating that:
Because of the difference in the definitions of “cocaine base” in the statute and the Guidelines after the amendment, defendants ... often will be sentenced under the statutory mandatory minimum to a higher sentence than would have been imposed under the Guidelines----
Heretofore, for most drug sentences, the Commission has chosen to calibrate the drug quantity table so that the sentencing ranges for defendants ... will equal or even exceed the mandatory mínimums set by Congress____
After the effective date of the amendment to the commentary to section 2Dl.l(c), however, a different method of calibration will exist for defendants who deal in cocaine base that is not crack.
4 F.3d at 155 (emphasis added).
Jackson urges this court to repudiate Palacio and follow United States v. Munoz-Realpe, 21 F.3d 375, 376-79 (11th Cir.1994). In Munoz-Realpe, the Eleventh Circuit disagreed with Palacio3 and abandoned a prior Eleventh Circuit decision, United States v. Rodriguez, 980 F.2d 1375 (11th Cir.1992) (per curiam), cert. denied, — U.S. -, 113 S.Ct. 3003, 125 L.Ed.2d 695 (1993), that, like Jackson I, had defined “cocaine base” (for both statutory and guideline purposes) to have a chemical meaning not limited to crack. See Rodriguez, 980 F.2d at 1377-78. Munoz-Realpe ruled that in accordance with the amendment 487 definition of “cocaine base” to mean “crack” for purposes of USSG 2D1.1(c), the Eleventh Circuit would henceforth construe the term “cocaine base” in 21 U.S.C. § 960(b)(1)(C) to mean “crack”.4 Munoz-Realpe, 21 F.3d at 377 (finding precedential force of Rodriguez “eroded by subsequent Congressional action” in allowing amendment 487 to take effect).
However, “prior opinions of a panel of this court are binding upon us in the absence of a change in the law by higher authority or our own in banc proceeding (or its equiva*1424lent)....” United States v. Moore, 949 F.2d 68, 71 (2d Cir.1991), cert. denied, 503 U.S. 988, 112 S.Ct. 1678, 118 L.Ed.2d 396 (1992). We are consequently bound to follow the ruling in Palacio that amendment 487 does not call for revision of the interpretation of § 841(b)(1)(A)(iii) that we rendered in Jackson I.
We proceed to consider Jackson’s constitutional claims. As to equal protection, Jackson correctly asserts that our ruling in United States v. Stevens, 19 F.3d 93, 96-97 (2d Cir.1994), subjected the challenged penalty provisions of § 841(b)(1) only to rational basis review because there was no claim in Stevens that their enactment was motivated by intentional discrimination. Jackson accordingly presents the legal and historical arguments in support of the proposition that the enhanced penalties imposed by § 841(b)(1) for cocaine base violations should be subjected to, and invalidated by, strict scrutiny rather than rational basis review because Congress enacted them with discriminatory intent. Since the oral argument of this appeal, however, we have considered and rejected this claim. See United States v. Moore, 54 F.3d 92, 96-99 (2d Cir.1995); see also United States v. Then, 56 F.3d 464, 466 (2d Cir.1995) (following Moore ).5
Finally, Jackson contends that the sentence imposed upon him violates the Eighth Amendment prohibition against cruel and unusual punishments because the penalty scheme for cocaine base offenses is arbitrary and capricious. This circuit has held in the Fifth Amendment context that the scheme is “rationally related to the legitimate governmental purpose of protecting the public against the greater dangers of crack cocaine.” Stevens, 19 F.3d at 97. The same reasoning is applicable to Jackson’s Eighth Amendment challenge.
Jackson also complains that the enhanced penalties for cocaine base in § 841(b) “allow[ ] for no exception, take[ ] into account no mitigating circumstances, and permit[] the judge no discretion whatsoever.” However, even mandatory sentences of life imprisonment without the possibility of parole do not violate the Eighth Amendment simply because they are mandatory. See Harmelin v. Michigan, 501 U.S. 957, 994-96, 111 S.Ct. 2680, 2701-02, 115 L.Ed.2d 836 (1991) (refusing to extend the requirement under the Eighth Amendment that an individualized determination is required for capital sentences to mandatory sentences of life imprisonment without parole). “Congress has the power to define criminal punishments without giving the courts any sentencing discretion.” Chapman v. United States, 500 U.S. 453, 467, 111 S.Ct. 1919, 1928, 114 L.Ed.2d 524 (1991).
The amended judgment of the district court is accordingly affirmed.