Opinion by Judge GRABER; Dissent by Judge PREGERSON.

Defendant Rogelio Banuelos-Rodriguez pleaded guilty in the United States District Court for the Central District of California to illegally reentering the United States after having been deported, in violation of 8 U.S.C. § 1326 . At sentencing, Defendant argued for a downward departure from the applicable Sentencing Guideline range on the ground that, had he been arrested in one of the other federal districts in California, he would have been offered a plea bargain that, in turn, would have resulted in a shorter prison term. The district court held that the disparity between the charging and plea-bargaining decisions of the United States Attorney for the Central District and those of the Unit *971 ed States Attorneys for the other federal districts in California was not a proper ground for departing from an otherwise applicable Guideline range. Defendant appeals, challenging only that ruling of the district court at sentencing. We affirm.

BACKGROUND

In August 1995, Defendant was charged in a one-count indictment with being an alien found in the United States after having been deported. Pursuant to a plea agreement, Defendant pleaded guilty to violating § 1326(a) and admitted facts that subjected him to the sentencing enhancement provided by § 1326(b)(2). 1 Specifically, Defendant acknowledged that he had been convicted of an aggravated felony, the sale of rock cocaine, and that he had three additional felonies on his record, including vehicular manslaughter. Under the Sentencing Guidelines, in the absence of departures, the applicable sentencing range was 70 to 87 months.

At sentencing, Defendant argued for a downward departure from the applicable sentencing range based on an alleged discrepancy between the length of sentences received by § 1326 violators prosecuted in the Central District of California and the length of sentences received by § 1326 violators prosecuted in the Southern District of California. According to a newspaper article that Defendant submitted to the district court, previously deported aliens who were arrested in the Southern District of California were eligible for that district’s “fast-track” program. See Thom Mrozek, Prosecutions on the Rise: U.S. Attorneys Take Varying Approaches to Illegal Re-Entry, L.A. Daily J., Sept. 21, 1995, at 1. Under the fast-track program in place at the time Defendant was convicted, “the vast majority of defendants [in the Southern District] — except those convicted of the most violent and depraved acts— [were] offered a deal under Section 1326(a), which carries a statutory maximum sentence of two years in prison.” Id. at 9. 2 “Those few defendants who face longer prison terms under 1326(b) are offered plea bargains that see their sentences top out at five years.” Id. The Northern and Eastern Districts of California had adopted similar programs, while the Central District had not. See id.

According to the article that Defendant presented to the court, the different charging and plea-bargaining policies that were used in California’s different federal districts resulted from individual United States Attorneys’ attempts to address the varying illegal immigration problems in their districts. The United States Attorney for the Central District prosecuted only those § 1326 violators with the worst criminal histories and then sought lengthy prison sentences for those convicted. The rationale behind that approach was that the best use of resources, in terms of deterrence and the protection of society, is *972 achieved by incapacitating for long periods of time those aliens who pose the greatest threat of committing future harm. See id. at 9.

On the other hand, again according to Defendant’s proffer, the United States Attorney for the Southern District decided to prosecute more § 1326 violators but to seek shorter prison sentences for most of those convicted. The Southern District’s fast-track program allowed the government to secure a large number of convictions with relatively little use of its resources. In most cases, under the fast-track program, the alien agreed to plead guilty before indictment, stipulate to deportation, and waive all rights to appeal the sentence. See id.; see also United States v. Estrada-Plata, 57 F.3d 757, 759 (9th Cir.1995) (describing the fast-track-program of the Southern District of California).

After considering this argument about sentencing disparity, the district court denied Defendant’s motion for a downward departure. The court held that this disparity is not a proper ground for departure: “[I]f the court accepts whatever has been bargained and then sentences pursuant to the guidelines, then I don’t see how any disparity in the plea bargain charging [among] the various districts adds up to a downward departure factor.” The court then sentenced Defendant to 70 months’ imprisonment, at the bottom end of the Guidelines range, and three years of supervised release. On appeal, Defendant contends that the district court erred in holding that it had no discretion to grant him a downward departure to equalize his sentence with the sentences of aliens with similar criminal backgrounds who, at the time of Defendant’s sentencing, were found in the Southern District of California after having been deported.

STANDARD OF REVIEW

We review for abuse of discretion a district court’s decision about departure from a Guidelines sentence:

Koon v. United States, 518 U.S. 81, 100 , 116 S.Ct. 2035 , 135 L.Ed.2d 392 (1996) (citation omitted).

DISCUSSION

1. Application of the Sentencing Guidelines

Defendant was convicted of violating 8 U.S.C. § 1326 . The applicable Sentencing Guideline for a violation of that statute is U.S.S.G. § 2L1.2, 3 which provides:

(Boldface type in original.)

Pursuant to the terms of his plea agreement, Defendant admitted that he had been deported after a conviction for an aggravated felony. Therefore, the district court properly calculated Defendant’s offense level as 21 (Base Offense (8) + Specific Offense Characteristics (16) — Ac *973 ceptance of Responsibility (3) = 21). Given Defendant’s criminal history category of V, the resulting sentencing range is 70 to 87 months’ imprisonment. See U.S.S.G. Ch. 5, Pt. A. The district court sentenced Defendant at the low end of that range.

Defendant does not contest that he violated § 1326(a) and was eligible for the aggravated-felony enhancement under § 1326(b)(2). Nor does Defendant contest that U.S.S.G. § 2L1.2, by its plain terms, applies to his offense of conviction. Nor does Defendant quarrel with the district court’s arithmetic.

2. “Mitigating Circumstance”

By statute, a district court may not depart from an applicable Guideline range “unless the court finds that there exists an aggravating or mitigating circumstance of a kind, or to a degree, not adequately taken into consideration by the Sentencing Commission in formulating the guidelines that should result in a sentence different from that described.” 18 U.S.C. § 3553 (b). Defendant contends that the disparity between the sentences received by similarly situated aliens in the Central District versus the Southern District is a mitigating circumstance that the Commission did not adequately take into consideration when it formulated the Guidelines.

The sentencing disparity at issue here results from policy choices made by different United States Attorneys in their respective districts. At the time that Defendant was sentenced, the United States Attorney in the Central District opted to concentrate on prosecuting those “worst” § 1326 violators who could be sentenced under § 1326(b). By contrast, the United States Attorney in the Southern District chose to prosecute more § 1326 violators and then offer the majority of them an opportunity to plead to a lesser offense. As a result, it was more likely that an illegal alien who was eligible for the enhancement provided by § 1326(b) would be sentenced under § 1326(b) if the alien was apprehended in the Central District.

We fail to see how the decision of the United States Attorney for the Southern District of California to pursue a particular prosecutorial policy in dealing with § 1326 violators in that district can be a “mitigating circumstance” with regard to Defendant or his crime. Cf. United States v. Ray, 930 F.2d 1368, 1373 (9th Cir.1991) (Kozinski, J., dissenting) (noting that, although the situation in which one co-defendant is sentenced under the Guidelines and another is sentenced during a period when the Ninth Circuit rejected the Guidelines may be “highly unusual,” it is not a “mitigating circumstance”). Nothing about the Southern District’s “fast-track” program lessens the severity of Defendant’s conduct or makes his criminal or personal history more sympathetic. The fact that, had Defendant been apprehended in the Southern District, he might not have been punished to the fullest extent of the law, does not make his otherwise lawful sentence less justified. Thus, the existence of differing prosecutorial policies regarding § 1326 violators is not a “mitigating circumstance.”

3. The Guidelines’ “Heartland” Analysis

Even if differing prosecutorial policies could be considered a mitigating circumstance within the meaning of the statute, the Guidelines themselves would preclude granting a downward departure based on a disparity of this nature. The commentary to the Guidelines provides in part:

U.S.S.G. Ch. 1, Pt. A, Intro, p.s. 4(b), at 5-6 (emphasis added). When defining the heartland of a particular offense, the “[Su *974 preme] Court has explained that the proper comparison is between the conduct of the defendant and the conduct of other offenders” who have been convicted of committing the same offense. United States v. Stevens, 197 F.3d 1263, 1268 (9th Cir.1999) (citing Koon, 518 U.S. at 104-05 , 116 S.Ct. 2035 ); see also United States v. Sanchez-Rodriguez, 161 F.3d 556, 561 (9th Cir.1998) (en banc) (providing that, to determine the heartland, a district court is to compare the defendant’s conduct with that of all defendants who are sentenced under the same Guideline). As noted, Defendant and his conduct fall squarely within the heartland of his offense of conviction.

The purpose of the Sentencing Commission was to establish Guidelines that “avoid[ ] unwarranted sentencing disparities among defendants with similar [criminal] records who have been found guilty of similar criminal conduct.” 28 U.S.C. § 991 (b)(1)(B) (emphasis added). In drafting the Guidelines, the Commission “sought reasonable uniformity in sentencing by narrowing the wide disparity in sentences imposed for similar criminal offenses committed by similar offenders.” U.S.S.G. Ch. 1, Pt. A, Intro, p.s. 3, at 2.

In other words, the Guidelines have sought to achieve uniformity in sentencing only by attempting to equalize the sentences of those who have engaged in similar criminal conduct, have similar criminal backgrounds, and have been convicted of the same offense. “The uniformity the Guidelines sought was designed to come from the specific provisions of the Guidelines itself, not from giving judges a broad discretion to ignore the Guidelines and increase [or decrease] sentences based on extraneous factors such as the punishment meted out to” those convicted of other offenses. United States v. Enriquez-Munoz, 906 F.2d 1356, 1360 (9th Cir.1990).

Here, Defendant agreed to plead guilty to violating § 1326(a) and to admit facts making him eligible for the enhancement provided by § 1326(b)(2). An alien who merely pleads guilty to a simple violation of § 1326(a) and an alien who pleads guilty to violating § 1326(a) and also admits facts demonstrating eligibility for the enhancement under § 1326(b)(2) are not pleading “guilty to essentially the same crime.” Id. at 1358. In the former case the alien is pleading guilty to being in this country illegally after having been denied admission, excluded, deported, or removed. See 8 U.S.C. § 1326 (a). In the latter case, the alien is pleading guilty to being in the United States illegally after conviction of an aggravated felony. See 8 U.S.C. §. 1326(b)(2). Granting a downward departure on the ground that Defendant received a longer sentence than other defendants who have been convicted of committing a different crime would be inappropriate.

Additionally, allowing sentencing departures grounded on the length of sentences received by others who engaged in similar conduct but were convicted of different offenses would require courts to “look behind ... plea agreements and assess the actual culpability of ... defendants.” Enriquez-Munoz, 906 F.2d at 1359 . Not only would this process impinge on prosecutors’ discretion in charging and plea bargaining, it also would require sentencing courts to conduct involved and cumbersome evidentiary hearings. There is no support for the contention that the Commission intended the Guidelines to produce such effects.

4. “Highly Infrequent”

Although the Commission recognized that departures from a Guidelines sentence, on grounds not mentioned in the Guidelines themselves, may be warranted, it expected that such departures would be “highly infrequent.” U.S.S.G. Ch. 1, Pt. A, Intro, p.s. 4(b), at 6; see also Koon, 518 U.S. at 96 , 116 S.Ct. 2035 (so stating). If the district court for the Central District could depart downward for all aliens convicted of violating § 1326(a) who are eligible for the subsection (b)(2) enhancement, on the ground that they would receive *975 longer sentences than illegal aliens with similar criminal histories in another district, departures would not be “highly infrequent.” Instead, they would be highly frequent. Moreover, logically under Defendant’s theory, a defendant sentenced in the District of Alaska or the District of Arizona could make the same argument as Defendant here, or could bring in evidence of charging and plea-bargaining practices in the District of South Carolina or the District of Maine. 4

5. The Guidelines’ Treatment of Prosecu-torial Discretion

To determine whether the Commission adequately considered a certain possible factor for departure, courts are to “consider only the sentencing guidelines, policy statements, and official commentary of the Sentencing Commission.” 18 U.S.C. § 3553 (b). Those portions of the Sentencing Guidelines that address prosecutorial discretion support our conclusion that departure is not permissible based on differing legitimate policies of United States Attorneys.

First, the Guidelines provide that “a sentencing court may control any inappropriate manipulation of the indictment through use of its departure power.” U.S.S.G. Ch. 1, Pt. A, Intro, p.s. 4(a), at 5 (emphasis added). By implication, the sentencing court may not use its departure power to impinge on a prosecutor’s legitimate exercise of discretion in charging a defendant.

Second, a sentencing court has the power to reject a plea agreement if it determines that the agreement does not “adequately reflect the seriousness of the actual offense behavior [or] that accepting the agreement will ... undermine the statutory purposes of sentencing or the sentencing guidelines.” U.S.S.G. § 6B1.2(a). The wording of that provision suggests that a court may accept or reject a plea agreement at the outset, but is not free to accept a plea agreement and then depart based on the inadequacy of that agreement. Moreover, the commentary to that section cautions that the power of a court to reject a plea agreement “does not authorize judges to intrude upon the charging discretion of the prosecutor.” U.S.S.G. § 6B1.2 comment., at 322.

As those provisions make clear, the Commission considered the effects that the exercise of prosecutorial discretion has on the uniformity of sentences. The Guidelines allow sentencing courts to take certain limited actions in narrow circumstances to address a prosecutor’s inappropriate exercise of discretion. In all other circumstances, the Guidelines do not give courts the authority to interfere with a prosecutor’s exercise of discretion in charging and plea bargaining by departing from an applicable Guideline range.

Defendant does not argue that the prosecutor inappropriately manipulated the charges against him or that his plea agreement fails to reflect the seriousness of his crime. Accordingly, the Guidelines required the district court to impose a sentence consistent with Defendant’s offense of conviction. See United States v. Thomas, 884 F.2d 540, 544 (10th Cir.1989) (“[The defendant] contends further that, under the guidelines, the prosecutor can control the length of a defendant’s sentence by management of the charging of offenses and plea bargaining practices. *976 [The defendant] does not show, however, how his rights were violated in this way. [The defendant] was convicted as charged following a one-count indictment; he offers no evidence of bad faith or discrimination on the part of the prosecutor at any time during the criminal proceedings.”), reasoning adopted in United States v. Fuentes, 925 F.2d 1191, 1193 (9th Cir.1991) (“We agree with the Tenth Circuit and adopt its analysis. The Sentencing Guidelines do not unconstitutionally enlarge the prosecutor’s influence over sentencing.”).

Additionally, although it is indisputable that the goal of federal sentencing reform was the elimination of unwarranted sentencing disparity, a review of the legislative history suggests that the disparity that Congress sought to eliminate did not stem from the exercise of prosecutorial discretion. See S.Rep. No. 225, 98th Cong., 2d Sess. 38, reprinted in 1984 U.S.C.C.A.N. 3182, 3221 (“These disparities ... can be traced directly to the unfettered discretion the law confers on those judges and parole authorities responsible for imposing and implementing the sentence.”). In fact, one of the primary criticisms of the Guidelines was that the sentencing regime would “simply shift discretion from sentencing judges to prosecutors.” Id. at 3246. Thus, it cannot fairly be said that Congress was seeking to reduce sentencing disparities arising from the exercise of prosecutorial discretion when the legislation that it enacted would, if anything, enhance that discretion. Congress was aware that the Guidelines would shift discretion to prosecutors and decided that judicial review of plea agreements would sufficiently alleviate problems in this area. See id. (“The concern is that the prosecutor will use the plea bargaining process to circumvent the guidelines recommendation.... The bill contains a provision designed to avoid this possibility. Under proposed 28 U.S.C. § 994 (a)(2)(D), the Sentencing Commission is directed to issue policy statements for consideration by Federal judges in deciding whether to accept a plea agreement. This guidance will assure that judges can examine plea agreements to make certain that prosecutors have not used plea bargaining to undermine the sentencing guidelines.”). In sum, the legislative history of the Guidelines also supports our conclusion that sentencing disparities arising from the charging and plea bargaining decisions of different United States Attorneys is not a proper ground for departing from an otherwise applicable Guideline range.

6. Separation of Powers

In Enriquez-Munoz , we noted that allowing a district court to depart in order to equalize the sentences of defendants who had pleaded guilty to committing different crimes (even if they had engaged in similar conduct) would implicate “the authority given to United States attorneys to negotiate plea bargains.” 906 F.2d at 1359 . Courts generally have no place interfering with a prosecutor’s discretion regarding whom to prosecute, what charges to file, and whether to engage in plea negotiations. See United States v. LaBonte, 520 U.S. 751, 762 , 117 S.Ct. 1673 , 137 L.Ed.2d 1001 (1997) (“[T]he discretion a prosecutor exercises when he decides what, if any, charges to bring against a criminal suspect[ ] ... is an integral feature of the criminal justice system, and is appropriate, so long as it is not based upon improper factors.”); see also United States v. Armstrong, 517 U.S. 456, 464 , 116 S.Ct. 1480 , 134 L.Ed.2d 687 (1996) (“United States Attorneys retain ‘broad discretion’ to enforce the Nation’s criminal laws.... In the ordinary case, so long as the prosecutor has probable cause to believe that the accused committed an offense defined by statute, the decision whether or not to prosecute, and what charge to file or bring before a grand jury, generally rests entirely in his discretion.”) (citations and internal quotation marks omitted); Wayte v. United States, 470 U.S. 598, 607 , 105 S.Ct. 1524 , 84 L.Ed.2d 547 (1985) (“Such factors as the strength of the case, the prosecu *977 tion’s general deterrence value, the Government’s enforcement priorities, and the case’s relationship to the Government’s overall enforcement plan are not readily susceptible to the kind of analysis the courts are competent to undertake.”).

We repeatedly have echoed that theme. See United States v. Duran, 41 F.3d 540, 544 (9th Cir.1994) (“If the prosecutor has probable cause to believe a defendant committed a crime, the decision of whether to prosecute and the charges to be filed rests with the prosecutor.”); United States v. Oakes, 11 F.3d 897, 899 (9th Cir.1993) (“[W]e have no jurisdiction to review prosecutors’ charging decisions, absent proof of discrimination based on suspect characteristics such as race, religion, gender or personal beliefs. This is true, even where the prosecutor’s decision ... was motivated primarily by a desire to impose a harsher sentence, and was inconsistent with the treatment given other defendants.... [A] “wide disparity’ between sentencing schemes of different jurisdictions does not violate equal protection, even where two persons who commit the same crime are subject to different sentences.”) (citations omitted); United States v. Palmer, 3 F.3d 300, 305 (9th Cir.1993) (“[Separation of powers concerns prohibit us from reviewing a prosecutor’s charging decisions absent a prima facie showing that it rested on an impermissible basis, such as gender, race or denial of a constitutiohal right.”) (footnote omitted); United States v. Redondo-Lemos, 955 F.2d 1296, 1299 (9th Cir.1992) (“Prosecutorial charging and plea bargaining decisions are particularly ill-suited for broad judicial oversight.... Such decisions are normally made as a result of careful professional judgment as to the strength of the evidence, the availability of resources, the visibility of the crime and the likely deterrent effect on the particular defendant and others similarly situated.”) (citation and footnote omitted).

Defendant has not alleged, nor is there any evidence in this record that tends to show, that any of the policies implemented and pursued by the United States Attorney for the Central District were based on impermissible factors such as racial or religious animosity. Quite the opposite appears to be true. According to the materials that Defendant himself presented, the United States Attorneys’ differing policies appear to have been considered attempts to address the unique illegal immigration problems faced by their individual districts.

Defendant’s argument that the Guidelines’ basic goal of uniform sentencing should be served by uniform charging practices must be made to the executive, not the judicial, branch. Judicial respect for prosecutorial discretion militates in favor of holding that courts may not depart from an applicable sentencing range on the ground that, had the defendant been prosecuted in another federal district by a different prosecutor, the defendant would have been able to negotiate a more favorable bargain.

7. Ninth Circuit Precedent

Finally, our prior decisions in analogous circumstances support the conclusion that a disparity of this kind cannot be the basis for a downward departure. In Enriquez-Munoz , the defendant had pleaded guilty to aiding and abetting an 18 U.S.C. § 922 (a)(6) violation by providing false statements in acquiring firearms. See 906 F.2d at 1357 . The applicable Sentencing Guideline provided for a prison term of four to ten months. The district court, however, departed upward and sentenced the defendant to 24 months’ imprisonment. See id. at 1357-58 & n. 1. The district court based its upward departure in part on the fact that a co-defendant had been sentenced to a 24-month prison term. See id. The government argued that it was appropriate for the district court to depart upward to equalize the sentences of the defendant and his co-defendant, because they had engaged in similar underlying criminal conduct. See id. at 1358 . This court disagreed and held that the district *978 court could not impose an upward departure to equalize the defendant’s sentence with that of his co-defendant, because the two defendants had not “pled guilty to essentially the same crime. To the contrary, [the defendant] negotiated a far more favorable plea agreement with the government than did his co-defendant.” Id. at 1358-59 .

Similarly, in United States v. Carpenter, 914 F.2d 1131 (9th Cir.1990), the court affirmed a district court’s upward departure that created a sentencing disparity between the sentences of co-defendants. The court noted that, for the same reason that a sentencing disparity could not justify an upward departure, a sentencing disparity did not preclude an upward departure if the departure was otherwise justified. See id. at 1135-36 .

In United States v. Mejia, 953 F.2d 461, 467 (9th Cir.1992), the defendant argued “that he should be granted a downward departure from the Sentencing Guidelines because his relative lack of culpability in comparison with [his co-defendant was] a mitigating circumstance not adequately taken into consideration by the Sentencing Commission.” However, this court held that a district court cannot depart for the purpose of avoiding unequal treatment of co-defendants. See id. at 468 (“Basic notions of fairness dictate that defendants should be sentenced in proportion to their crimes.... A downward departure to correct sentencing disparity brings a defendant’s sentence more into line with his or her codefendant’s sentence, but places it out of line with sentences imposed on all similar offenders in other cases.”).

In sum, Enriquez-Munoz, Carpenter, and Mejia stand for the proposition that the equalization of sentences is an improper ground for departure if the court is attempting to equalize the sentences of co-defendants who are convicted of committing different offenses, even if their behavior was similar. We see no reason to limit that principle to cases involving the sentences of co-defendants. 5 We hold that a district court may not grant a downward departure from an otherwise applicable Guideline sentencing range on the ground that, had the defendant been prosecuted in another federal district, the Defendant may have benefited from the charging or plea-bargaining policies of the United States Attorney in that district.

AFFIRMED.

. When Defendant was sentenced, § 1326(a) and § 1326(b) were understood to be separate offenses. See United States v. Gonzalez-Medina, 976 F.2d 570, 572 (9th Cir.1992). In 1998, the Supreme Court held that subsections (b)(1) and (b)(2) were sentencing enhancements for a violation of § 1326(a). See Almendarez-Torres v. United States, 523 U.S. 224, 235 , 118 S.Ct. 1219 , 140 L.Ed.2d 350 (1998).

. As noted, Defendant was convicted and sentenced before the Supreme Court decided Al-mendarez-Torres. At that time, most fast-track districts allowed § 1326 violators to plead guilty to a simple violation of § 1326(a), which provided for a two-year maximum sentence, instead of the higher statutory maximums for § 1326(b)(1) and (b)(2). In response to Almendarez-Torres , some fast-track prosecutors have altered their programs by allowing persons charged under § 1326 to plead guilty to a violation of 8 U.S.C. § 1325 , which carries a statutory maximum sentence of 30 months' imprisonment. See Alan D. Bersin & Judith S. Feigin, The Rule of Law at the Border: Reinventing Prosecution Policy in the Southern District of California, 12 Geo. Immigr. L.J. 285 , 310 n. 26 (1998). Under both the past and the present regimes, prosecutors in fast-track districts are agreeing, in return for a guilty plea, to seek conviction for an offense that carries a lower sentence under the Guidelines.

. All references are to the November 1, 1995, version of the Sentencing Guidelines.

. This possibility is more than speculative. In United States v. Bonnet-Grullon, 212 F.3d 692 (2d Cir.2000), the defendants pleaded guilty to reentering the United States after having been deported following conviction of an aggravated felony. See 8 U.S.C. § 1326 (a) & (b)(2). They argued that the United States District Court for the Southern District of New York should have considered a downward departure on the basis of the policy followed by the United States Attorney’s Office in the Southern District of California. The Second Circuit held, as we do here, that the district court "lacked the authority to depart on the basis of that interdistrict sentencing disparity,” which results from the exercise of prosecutorial discretion. Id. at 693 .

. We recognize that, in United States v. Ray, 930 F.2d 1368 (9th Cir.1991), we approved a downward departure to correct a disparity between the sentences of co-defendants. In that case, however, the sentencing disparity was created when certain defendants were sentenced under the Guidelines and other defendants were sentenced during the brief period in which the Ninth Circuit had declared the Guidelines unconstitutional. See Gubiensio-Ortiz v. Kanahele, 857 F.2d 1245 (9th Cir.1988) (declaring the Sentencing Guidelines unconstitutional), overruled by Mistretta v. United States, 488 U.S. 361 , 109 S.Ct. 647 , 102 L.Ed.2d 714 (1989). The holding in Ray has been limited to the rare situation in which certain co-defendants are sentenced under the Guidelines while others are not. See United States v. Mejia, 953 F.2d 461 , 468 n. 2 (9th Cir.1992) (so stating); see also United States v. Boshell, 952 F.2d 1101, 1107-08 (9th Cir.1991) (approving a district court's downward departure where certain co-defendants were sentenced before, and others were sentenced after, the Guidelines took effect).