MURNAGHAN, Circuit Judge:
Michael Bolick has appealed his conviction for conspiring to sell, and selling, cocaine. Bolick’s primary contention is that the trial court impermissibly admitted prior consistent statements of government witnesses who had not yet been impeached. He also contends that the trial court impermissibly allowed the government to create a prejudicial “drug atmosphere” at trial under the guise of “background” evidence.
I
In early September 1987, undercover government agent D.C. Ramsey arranged to purchase an ounce of cocaine from Ray Samuel Dicks. Agent Ramsey had established a relationship with Dicks by purchasing drugs from him on several previous occasions. On September 3, Agent Ramsey gave Dicks $1500 with the understanding that Dicks would acquire the ounce of cocaine. Dicks allegedly acquired the cocaine from defendant Michael Bolick on September 8. Dicks in turn provided Agent Ramsey with the ounce of cocaine. At no time did Agent Ramsey have any direct contact with defendant Bolick.
The government’s case against Bolick relied exclusively on the observations of three witnesses who were present when Bolick allegedly supplied Dicks with the cocaine for Agent Ramsey’s purchase. Because he had no direct contact with Bolick, Agent Ramsey could provide no direct evidence against him. The three government witnesses were Ray Dicks, his wife Amy Blackburn Dicks, and Bartley Blackburn. The Dickses were charged as co-conspirators but were not tried with Bolick. Blackburn was not charged for any crime related to Agent Ramsey’s purchase of the ounce of cocaine.
Ray Dicks, Amy Dicks, and Blackburn might well have worn signs saying, “Impeach me.” Ray Dicks was to testify against Bolick in exchange for a seven year cap on his sentence for pending charges of sale and distribution of LSD and cocaine. At age 17 Dicks was convicted of a marijuana charge and burglary, serving a two and one-half year prison term. He has been convicted on three separate occasions for driving while intoxicated and has been convicted of at least five additional traffic offenses. He also has convictions for carrying a concealed weapon, and possibly for escaping from a Georgia penitentiary. All this in a 28-year lifetime. Amy Dicks had been “charged for shoplifting and [had] two DWI’s.” She was to testify against Bolick in exchange for a government recommendation that her sentence on pending charges not exceed four years. Blackburn’s credentials begin with a federal parole violation. Blackburn had apparently been on probation for possession of a sawed-off shotgun when he was arrested for distribution of LSD. Blackburn also has suffered two convictions for breaking and entering, as well as convictions for destruction of private property and drunk driving. He also had charges pending for conspiring to sell acid and selling marijuana.
The controversy on appeal concerns the trial strategy adopted by the government which has the appearance of having been an attempt to minimize the unpalatability of its witnesses. Bolick’s two allegations of error concern, specifically, the testimony of the first government witness, Agent Ramsey. Agent Ramsey began his testimony by recounting the manner in which [137]*137he established his relationship with Dicks. That testimony included mention of three occasions on which Dicks sold Agent Ramsey L.S.D. Agent Ramsey testified that he purchased from Dicks 1200 hits of L.S.D. for about $3,750. Bolick is not alleged to have been involved in those sales.
After testifying to his limited knowledge of events between giving Dicks the $1500 for the cocaine purchase on September 3 and receiving the cocaine on September 8, Agent Ramsey began describing discussions he had with the Dickses and Blackburn (“the declarants”). The discussions in question took place on two occasions (April 1988 and August 1988), after the Dickses had been charged and long after the alleged conspiracy involving Bolick and the Dickses was over. Agent Ramsey’s description of what the declarants had told him was detailed, consuming about eighteen pages of transcript. Agent Ramsey described separately his discussions with each of the declarants.
Of greatest importance for our purposes was that the district court, over objection, allowed Agent Ramsey to testify that each of the declarants told him that it was Bolick who had supplied the ounce of cocaine that Agent Ramsey eventually purchased. Thus, before any of the declarants had taken the stand, the jury was informed three times by arrant hearsay that each of the declarants told Agent Ramsey that Bolick was guilty. In response to the first of the numerous objections by Bolick’s counsel, the district court gave the jury the following instruction:
Ladies and gentleman of the Jury, I will instruct you concerning [a] point of law — at this point, the testimony of this witness, concerning the transactions and discussions that he had with Mr. Ray Dicks, as to statements made by Mr. Dicks, will be taken by you not for the proof of what Mr. Dicks is said to have stated, but as corroboration of Mr. Dicks’ testimony to come later in this case.
It may seem like a southern [sic] distinction to you, but I want you to remember it and apply what I’m telling you; to your deliberation. That is, to repeat the point. The testimony being offered here as to what Mr. Ray Dicks said, is not being — shall not be received by you as statements for the proof of what Mr. Ray Dicks said to this witness. But if you later find that Mr. Dicks made the statements which this witness says he made, then you may receive this testimony as corroboration of what Mr. Ray Dicks later says that he said, if you find that it does in fact corroborate this testimony.
Bolick’s counsel repeated his objection to Agent Ramsey’s recitation of Amy Dicks’ out-of-court statements at the time Agent Ramsey recounted them, although he did not do so for Agent Ramsey’s testimony as to Blackburn’s declarations. On each objection, the district court referred the jury to the instruction cited above.
After Agent Ramsey had testified, the government called each of the declarants as witnesses. The government elicited from each declarant the same testimony inculpating Bolick that Agent Ramsey had recited while on the stand. (There were slight variations between Amy Dicks’ actual testimony and her declarations as presented by Agent Ramsey.) On cross-examination, Bolick’s counsel tried to impeach each of the declarants. The only witness called by the defense was Bolick, who admitted going to the Dickses’ residence, where the cocaine transaction took place, but denied selling the cocaine.
The jury convicted Bolick and he was sentenced to a six-year prison term and a $5,000 fine.
II
We begin our analysis with Bolick’s contention that the district court erred by allowing Agent Ramsey to recite each of the declarants’ out-of-court statements inculpating Bolick before any of them had been impeached.
A
Federal Rule of Evidence 801(d)(1)(B) provides that a prior statement is not hearsay if
[138]*138the declarant testifies at the trial or hearing and is subject to cross-examination concerning the statement, and the statement is consistent with the declarant’s testimony and is offered to rebut an express or implied charge against the declarant of recent fabrication or improper influence or motive.
The government contends, and the district court instructed, that Agent Ramsey’s testimony as to the declarants’ prior consistent statements was not admitted for the truth of the matter asserted but for mere “corroboration,” by which it presumably means “rehabilitation.” There is considerable authority for the proposition that the requirements of Rule 801(d)(1)(B) must be met only when a prior consistent statement is offered for its truth and that general principles of trial court discretion apply when a prior consistent statement is admitted for some other purpose such as rehabilitation or background. See, e.g., United States v. Mazza, 792 F.2d 1210, 1215 (1st Cir.1986), cert. denied, 479 U.S. 1086, 107 S.Ct. 1290, 94 L.Ed.2d 147 (1987); United States v. Pierre, 781 F.2d 329, 333 (2d Cir.1986); United States v. Rubin, 609 F.2d 51, 66-70 (2d Cir.1979) (Friendly, J., concurring), aff'd on grant of certiorari limited to other issue, 449 U.S. 424, 101 S.Ct. 698, 66 L.Ed.2d 633 (1981); United States v. Obayagbona, 627 F.Supp. 329, 335-38 (E.D.N.Y.1985) (Weinstein, J.). But see generally Pierre, supra (discussing arguable split within Second Circuit law). Although we have not had occasion to address it squarely, we may have endorsed the proposition in United States v. Parodi, 703 F.2d 768, 785-86 (4th Cir.1983) (citing with apparent approval language from Judge Friendly’s concurrence in Rubin, supra). But cf. United States v. Henderson, 717 F.2d 135, 138 n. 1 (4th Cir.1983) (indicating, in context of separate issue of whether Rule 801(d)(1)(B) requires absence of motive to fabricate at time prior consistent statement made, that Parodi should be read narrowly), cert. denied, 465 U.S. 1009, 104 S.Ct. 1006, 79 L.Ed.2d 238 (1984).
Fortunately, for purposes of our opinion, we can assume, without deciding, that the prior consistent statements were admitted as rehabilitation and that they are not subject to the requirements of Rule 801(d)(1)(B). Even with the benefit of such assumptions, the admission of the statements was erroneous because the admission preceded impeachment of the declarants. Although the legal support for our conclusion follows shortly, we note that the requirement that impeachment must precede rehabilitation should surprise no one. For how can one rehabilitate what has not yet been discredited? As Webster’s instructs, to rehabilitate is “to restore to good repute by vindicating: clear of unjust or unfounded charges: reestablish the good name of.” Webster’s Third New International Dictionary 1914 (1976).
Although “the trial court has traditionally exercised the broadest sort of discretion in controlling the order of proof at trial,” Huddleston v. United States, 485 U.S. 681, 688, 108 S.Ct. 1496, 1500, 99 L.Ed.2d 771 (1988) (rejecting argument that, under Fed. R.Evid. 404(b), trial court must make preliminary finding as to similar act evidence before such evidence is presented to jury), a trial court’s decisions on such matters are not immune from review. Close scrutiny is particularly appropriate when a trial court departs from established practices. We think that was the case here. For “one general principle, operative under both case law and the Federal Rules of Evidence, is that in the absence of an attack upon credibility no sustaining evidence is allowed.” McCormick on Evidence, § 49, at 115 (3d ed. 1984) (and cases cited therein); accord J. Weinstein and M. Berger, Weinstein’s Evidence, ¶ 607[08], at 607-111-12 (1989) (and cases cited therein). We are among the courts to adhere to that time-honored principle. See Henderson, 717 F.2d at 137 (“As a general rule a witness’s credibility may not be rehabilitated unless it first has been challenged;” citing Fed.R.Evid. 608(a)(2)); see also United States v. Porter, 821 F.2d 968, 974 (4th Cir.1987) (citing with approval United States v. Hilton, 772 F.2d 783, 786 (11th Cir.1985), where the “fundamental evidentiary principle [that] evidence of a witness’ truthful character is [139]*139admissible only after character for truthfulness has been attacked” required the conclusion that “when the bolstering testimony goes to the character for truthfulness of the only witnesses to repudiate the defendants’ claim, admission of such testimony is also reversible error.”), cert. denied, 485 U.S. 934, 108 S.Ct. 1108, 99 L.Ed.2d 269 (1988). Thus, even under general principles of rehabilitation evidence, wholly apart from any considerations of Rule 801(d)(1)(B), the district court’s admission of the statements prior to any attack on the declarants’ credibility was improper.
Moreover, in addition to affirming the general principle that impeachment must precede rehabilitation, our cases have long recognized that principle in the specific context presented here: rehabilitation by prior consistent statement prior to impeachment. See United States v. Weil, 561 F.2d 1109, 1111 (4th Cir.1977) (“Corroborative testimony consisting of prior, consistent statements is ordinarily inadmissible unless the testimony sought to be bolstered has first been impeached.”); United States v. Leggett, 312 F.2d 566, 572 (4th Cir.1962) (“The decisions following the established rule are in agreement in holding that proof of prior consistent statements is not admissible unless and until there has been some impeachment of the witness ... and that they cannot be shown as a part of the evidence in chief.”); Schoppel v. United States, 270 F.2d 413, 417 (4th Cir.1959) (“Where a cross-examiner has endeavored to discredit a witness by prior inconsistent statements, it is sometimes permissible to offset the damage by showing prior consistent utterances. It is not proper, however, in chief to seek corroborative support of a witness by showing that after the event under inquiry and before the trial he made statements to the same effect.”) (citations omitted).
The government can seek no refuge in the fact that a limiting instruction from the court accompanied the prior consistent statements. As noted above, the district court instructed the jury as follows:
Ladies and gentleman of the Jury, I will instruct you concerning [a] point of law — at this point, the testimony of this witness, concerning the transactions and discussions that he had with Mr. Ray Dicks, as to statements made by Mr. Dicks, will be taken by you not for the proof of what Mr. Dicks is said to have stated, but as corroboration of Mr. Dicks’ testimony to come later in this case.
It may seem like a southern [sic] distinction to you, but I want you to remember it and apply what I’m telling you; to your deliberation. That is, to repeat the point. The testimony being offered here as to what Mr. Ray Dicks said, is not being — shall not be received by you as statements for the proof of what Mr. Ray Dicks said to this witness. But if you later find that Mr. Dicks made the statements which this witness says he made, then you may receive this testimony as corroboration of what Mr. Ray Dicks later says that he said, if you find that it does in fact corroborate this testimony.
As the emphasized portion shows, the instruction is critically incomplete. The instruction does distinguish between the concept of acceptance for the truth of the matter asserted and acceptance as corroboration and it does recognize the need for the prior statement to be consistent with the declarant’s subsequent testimony. However, the instruction omits mention of the crucial and dispositive factor: it does not instruct the jury that it may consider the statements only if the declarant is subsequently impeached by defense counsel. The admission of the evidence, therefore, cannot be defended by means of the ostensibly precautionary instruction given below. Cf. Leggett, 312 F.2d at 571 (court finds ambiguity and inadequacy in instruction that informed jury it could consider evidence for purpose of corroboration, “if you find that it does corroborate” the declarant).
The very understandable difficulty that the district court faced in formulating the instruction is reflective of one of the reasons supporting the traditional requirement that actual impeachment must precede the use of prior consistent statements for rehabilitation. We have great difficulty believ[140]*140ing that a jury can appreciate the distinction, in this context, between substantive evidence and rehabilitative evidence. If admitted as substantive evidence, the declarations would tend to show that Bolick was guilty. If admitted as rehabilitation, the declarations would tend to show that the declarants were telling the truth when they said that Bolick was guilty. If Bolick’s jury consisted of anything less than the fathers of modern philosophy, even a technically correct instruction probably would not have prevented the jury from overlooking the fine distinction between the two uses of the evidence and the jury probably would have used Agent Ramsey’s testimony as direct evidence of Bolick's guilt. See New Mexico v. Lucero, 109 N.M. 298, 784 P.2d 1041, 1046 (1989) (expressing the same belief and commenting that asking a jury to recognize the distinction “would be like asking a jury to consider a defendant’s confession, not for the truth but only [for the fact] that he made it.”) That inherent high risk of prejudice animates our conclusion that the search for comfort from the court’s instruction is fruitless.
If the impeachment had occurred first, the district court could have simply instructed the jury to accept Agent Ramsey’s testimony as rehabilitation of the declarants’ testimony and not as substantive evidence. Instead, the district court had to tell the jurors to wait until the declarants testified before deciding what to do with the declarations. It seems excessive to ask even the conscientious juror, who is probably still trying to absorb the distinction between prior consistent statements as substantive evidence and such statements as rehabilitation, to condition registration in his mind of each of the declarations on whether the declarant ultimately so testified and whether defense counsel subsequently impeached.
Given that the district court veered off of a well-paved road, we accord it considerably less deference than would usually be the case, and we conclude that the admission of the prior consistent statements before impeachment was error, even if the statements were offered only for rehabilitation.
B
Although we have concluded that admission of the prior consistent statements before impeachment was error, we must determine whether such error requires reversal. Courts that have found error in situations such as the one before us have carefully scrutinized the evidence at trial, and on occasion have concluded that the district court’s error was harmless. However, because the district court’s error actually and substantially prejudiced Bolick’s case and the considerations that have led other courts to excuse such error are here absent, we conclude that Bolick’s conviction must be reversed.
Two key facts influence our assessment of the harm to Bolick’s case resulting from the district court’s error. First, the government’s entire case against Bolick consisted of the declarations to which Agent Ramsey improperly testified, namely, the declarants’ statements that Bolick supplied the cocaine. Agent Ramsey himself had no first hand knowledge of Bolick’s involvement. Second, the character for veracity of the declarants was extremely doubtful. Those facts indicate that admission of the declarations was damaging in three ways. First, Agent Ramsey’s testimony doubled the number of times the jury heard that Bolick “did it;” second, the fact that the declarations emanated from the mouth of a law enforcement officer with no discreditable record lent an appearance of credibility to the declarations that would have otherwise been absent; and, third, Bolick was deprived of the opportunity to cross-examine the declarants immediately upon the appearance (through Agent Ramsey’s recitation) of the declarations because the declarants were not yet on the witness stand. In short, before the government had put on the first witness that was to supply inculpatory evidence, the jury had been told three times, by a credible witness, in statements that were effectively immune from cross-examination, that Bolick was guilty.
In Mazza, supra, the district court had allowed two government agents to describe [141]*141“strongly incriminating” statements that a government witness had made to them before the government witness testified at trial. 792 F.2d at 1215. The defendants complained that the effect of the agents’ testimony was to allow the government to present its case against the defendant three times (once from the declarant/witness and once from each of the two agents). Id. The defendants argued that the government witness in question was highly untrustworthy and the government therefore had gained an unfair advantage at trial. Id. In concluding that “both reason and authority indicate the appellants are right about the inadmissibility of the challenged testimony of the government agents,” even though the statements were admitted only for background, see id. at 1215, the First Circuit pointed to three considerations, two of which help to illustrate the harm to Bolick in this case. First, the amount of out-of-court statements was large. As in this case, the Mazza witness’ statements “pervaded the direct examination of the government agents.” 792 F.2d at 1215. As in this case, “the government effectively managed to have the jury hear a second-hand account of [the witness’] entire story through witnesses whose credibility the jury was less apt to question.” Id. Although Agent Ramsey did not present each of the declarants’ entire story, he presented much of it and, in particular, the crucial claim that Bolick sold the cocaine. Second, the Mazza court found a high risk that the out-of-court statements would sway the jury because the testimony might have shown facts not later corroborated and “would also likely bolster the credibility of the informer ... before he took the stand.” 792 F.2d at 1215. See also United States v. Mancillas, 580 F.2d 1301, 1309-10 (7th Cir.) (“to allow testimonial repetition of a declarant’s out-of-court charge that the defendant would engage or was engaged in specific criminality would seem to create too great a risk that [prejudice will outweigh probative value.] That risk cannot be justified simply to set forth the background of the investigation.”), cert. denied, 439 U.S. 958, 99 S.Ct. 361, 58 L.Ed.2d 351 (1978). In logic that applies equally to this case, the Mazza court wrote that “the jury was particularly likely to consider these out-of-court declarations for their truth, for they directly implicated the defendants in the specific acts at issue.” 792 F.2d at 1215-16. We find insightful the Mazza court’s assessment of the effect of the wrongly admitted evidence and we think that Bolick was similarly harmed by the admission of the prior consistent statements here at issue.
Keeping in mind the harm done by admission of the evidence, we now examine the record to see if other events at trial cured the harm Bolick suffered. We draw guidance from Mazza, where the court carefully compared the substance of the improperly admitted evidence with other corroborating evidence. 792 F.2d at 1217-21. In Mazza, for three of the declarations, one of which was corroborated by a tape recording and another of which was corroborated by first hand testimony of another government agent, the court was “satisfied that the admissible testimony overwhelmingly established the defendants’ guilt, and [the court was] therefore virtually certain that admission of the agents’ improper testimony ... did not affect the jury’s judgment.” Id. at 1221 (emphasis added). As to four other such declarations, the Mazza court was troubled but nonetheless affirmed because “the tape recordings and other independent evidence [other than the contents of the witness’ testimony recounted by the government agents] presented an overwhelming case.” Id. (emphasis added). Similarly, in Mancillas, supra, reversal was not required because each portion of the improperly admitted prior consistent statement was corroborated by evidence other than the same statement later being uttered by the declarant. See 580 F.2d at 1310-11. Our approach has been generally the same. See Leggett, 312 F.2d at 573 (error not harmless because evidence at trial was in conflict and improperly admitted declarations corroborated one version of the evidence); see also Porter, 821 F.2d at 974 (error harmless in large part because “the evidence of guilt was sufficient without [the witness’] testimony [and the witness’] evi[142]*142dence was corroborated”); Schoppel, 270 F.2d at 417 (in context of eleven-day proceeding, court found error harmless because it was “left with the firm conviction that no actual injury has been done to the defendant’s substantial rights”).
Applying these cases, we find that nothing in the subsequent proceedings cured the harm caused by the trial court’s error. If the improper declarations are extirpated from the record, the evidence against Bolick becomes far short of that necessary to support a conviction. Even if we were to excise only Agent Ramsey’s testimony, thereby allowing the declarants’ subsequent inculpatory statements to remain, the dubious character of the declarants still would prevent us from comfortably concluding that Bolick would have nonetheless been convicted.
Nor is the government’s case saved by the fact that the declarants were eventually impeached by Bolick’s counsel. The cases in which courts have found error to be harmless due to subsequent impeachment are distinguishable. See United States v. Lopez, 584 F.2d 1175, 1180 (2d Cir.1978) (distinguishable on grounds that (a) court based affirmance in part on presence of other incriminating evidence and (b) absence of objection below prompted court to apply the plain error standard of review); United States v. Simmons, 567 F.2d 314, 321-22 (7th Cir.1977) (distinguishable on grounds that improper hearsay was in form of prosecutorial statement during opening argument which court ordered stricken and later admitted after impeachment, unlike the ongoing condoned procedure in Bolick’s case). In United States v. Smith, 746 F.2d 1183 (6th.Cir.1984), where the declarant testified and was impeached on cross examination, the court observed that the prior consistent “statement was introduced before the witness making it had even taken the stand. Under these circumstances, the prior-consistent-statement exception simply cannot apply.” Id. at 1185 (emphasis in original).
Application to our case of the Smith court’s refusal to excuse improper admission of a prior consistent statement on the grounds of subsequent impeachment makes sense for two reasons. First, as noted above, the manner in which the evidence was presented allowed the government unfairly to establish Bolick’s guilt in the minds of the jurors before any of the declarants had testified. More generally, particularly where, as here, the prior consistent statement is being used against a criminal defendant, affirmance on the basis of subsequent impeachment would present defense counsel in subsequent cases with a choice they should not be forced to make. In such situations, defense counsel would have to choose between impeaching the witness (thereby increasing the likelihood of a favorable jury verdict but decreasing the likelihood of success on appeal) or not impeaching the witness (thereby decreasing the likelihood of a favorable jury verdict but increasing the likelihood of success on appeal). Such inconsistency of incentives for defense counsel also needlessly creates a tension between the system’s interests in, on the one hand, just results, and, on the other hand, avoidance of manufactured appeals. Although defense counsel routinely must make tough tactical choices, we will not adopt a rule that condones putting the defense in such a predicament by virtue of a prosecutorial trial tactic that is acknowledged to be improper. Where the preventative medicine is as simple as requiring that the proponent of a prior consistent statement wait until the declarant has been impeached, we see no reason to excuse failure to comply with what is a simple rule on the grounds of subsequent impeachment. But cf. Simmons, 567 F.2d 321-22 (subsequent impeachment “was a tactical decision made by the defendant by which he assumed the risk of the Government’s rebuttal”).
We have previously indicated our preparedness to vacate convictions where the government has improperly relied upon out-of-court statements, particularly when those statements effectively establish the defendant’s guilt. See, e.g., United States v. Brown, 767 F.2d 1078 (4th Cir.1985). We also have previously indicated that impeachment should precede prior consistent statement rehabilitation. In Mazza, in [143]*143summing up its exhaustive review of the evidence to determine whether the improper admission of prior consistent statements was reversible error, the court described its “results in detail, in part to show precisely how inadequate care in the conduct of a trial can convert an overwhelmingly strong prosecution case into a difficult issue on appeal.” 792 F.2d at 1217. Here, the prosecution case was considerably less than overwhelming. The concerns, in any event, are far broader and more general than the concerns merely of the instant case. Accordingly, the conviction of Michael Bolick must be reversed.
III
Bolick also argues that the district court committed reversible error by permitting Agent Ramsey to testify that Ray Dicks had sold L.S.D. to Agent Ramsey on three prior occasions. Bolick complains that the testimony created a “drug atmosphere,” which unfairly prejudiced him by causing the jury to associate him with numerous drug sales in which he was not in fact involved.
Since the case must be reversed and remanded for a new trial for the foregoing reasons, and the resolution of the issues involved on the second point is shrouded in doubt, we take no stand on a matter which may not arise on trial, or arise in a substantially different setting. Sufficient to the day is the evil thereof.
Sufficient thereto, the evil thereof also applies to Bolick’s contention that the cumulative effect of the testimony deprived him of a fair trial.
IV
For the foregoing reasons, the decision of the district court is
REVERSED AND REMANDED FOR A NEW TRIAL.