ORDER
PER CURIAM.On consideration of appellee’s petition for rehearing filed September 4, 1990 and appellant’s opposition thereto, it is
ORDERED, by the Court, that the petition for rehearing be granted in part and denied in part, and that Section II of our prior opinion be withdrawn and replaced by Section IV of the opinion filed herein, and point (2) of the Summary relating thereto be withdrawn and replaced by the following: “(2) The District Court’s jury instructions on Count 9 did not, taken as a whole, pose a genuine risk that the jury would be confused.” The reasons are set forth more fully in the opinion of the court filed herein this date.
Opinion dissenting as to Parts I, II & III filed by Chief Judge WALD.
PER CURIAM:
In its petition for rehearing, the Independent Counsel (“IC”) has raised several new issues regarding our original disposition. As we explain below, we believe that all but one of the IC’s claims lack merit. We therefore grant in part and deny in part the petition for rehearing and modify our original opinion, 910 F.2d 843, accordingly.
I. Immunized Testimony at Trial
The IC claims that we misapplied United States v. Rinaldi, 808 F.2d 1579 (D.C.Cir.1987), in remanding “for a massive inquiry into ‘the taint of the testimony and the derivation of the testimony.’ ” Petition for Rehearing at 7-8 (“Pet. for Reh’g”) (quoting Majority Opinion 910 F.2d at 866 (“Maj. Op.”) (emphasis in original)). The IC’s argument rests on the ipse dixit that “the prosecution’s freedom from taint establishes that its evidence was necessarily derived independently” and therefore that the inquiry mandated by Rinaldi would be “superfluous.” Pet. for Reh’g at 8. This bold proposition, however, would convert Kastigar’s total prohibition on use, Kastigar v. United States, 406 U.S. 441, 453, 92 S.Ct. 1653, 1661, 32 L.Ed.2d 212 (1973), to a mere ban on significant prosecutorial expo*942sure to the immunized testimony. It simply does not follow that insulating prosecutors from exposure automatically proves that immunized testimony was not used against the defendant. Kastigar is instead violated whenever the prosecution puts on a witness whose testimony is shaped, directly or indirectly, by compelled testimony, regardless of how or by whom he was exposed to that compelled testimony. Were the rule otherwise, a private lawyer for a witness sympathetic to the government could listen to the compelled testimony and use it to prepare the witness for trial. The government would presumably thereby gain the advantage of use of the immunized testimony so long as it did not actually cooperate in that effort. This interpretation of Kastigar (“Look ma, no hands”) pressed by the IC, if accepted, would enormously increase the risk of providing immunized testimony. To reject it, it is unnecessary to decide whether, as North asserts, particular significance should be placed on the fact that other government personnel in the legislative and executive branches outside the Independent Counsel’s office were, after exposure to immunized testimony, actively involved in preparing witnesses.
Indeed, Rinaldi explicitly recognizes that witnesses’ exposure to immunized testimony can taint their trial testimony irrespective of the prosecution’s role in the exposure and that an inquiry is therefore necessary into whether the content of witnesses’ testimony was derived from or motivated by the immunized testimony. It specifically mandates an inquiry into what a witness knew prior to exposure to the immunized testimony and what information she gleaned from that exposure: “[tjhere is accordingly a question of fact as to how much Reardon [the witness] knew prior to that meeting [at which she was exposed to the immunized testimony] and what additional knowledge, if any, she may have gained as a result of listening to Rinaldi’s testimony.” 808 F.2d at 1583. And even where the witness testifies from personal knowledge, use within the meaning of Kastigar may occur, as Rinaldi points out, if the immunized testimony influenced the witness’ decision to testify. Rather than recognizing, as the IC claims, that a Kastigar hearing may not focus on the “psychological processes of witnesses,” Pet. for Reh’g at 7 n. 4, Rinaldi directed inquiry into whether a witness’ testimony “was motivated by, and therefore indirectly derived from, Rinaldi’s immunized statements to the police.” 808 F.2d at 1584 n. 7 (emphasis added).1 Our opinion is thus entirely consistent with Rinaldi in calling for an inquiry on remand into the content and circumstances of witnesses’ testimony.
Our dissenting colleague does not disagree with us on this central point so vigorously disputed by the IC — that the content and circumstances of testimony given by a witness exposed to the defendant’s immunized testimony may constitute “use” of the immunized testimony in violation of a defendant’s constitutional rights regardless of the prosecutor’s “fault.” But she does contend that we have extended Rinaldi by insisting that the testimony of any witness exposed to the immunized testimony be “pre-recorded” in much the same way as prosecutors memorialize their investigative material, including witnesses’ statements, so as to be able to prove in a Kastigar hearing that the government has obtained no leads from the immunized testimony. We did not, however, set forth such a requirement; we only said this burden “may” be met by “cannpng]” the testimony beforehand, Maj.Op. at 872-873, just as wise prosecutors meet their burden of showing independent investigation by “canning” the results of the investigation before the defendant gives immunized testi*943mony.2
To be sure, if such steps are not taken, it may well be extremely difficult for the prosecutor to sustain its burden of proof that a witness exposed to immunized testimony has not shaped his or her testimony in light of the exposure, or as the Rinaldi court observed, been motivated to come forward and testify in light of the immunized testimony. But we surely did not mean to preclude the use of any techniques of which we are not aware, nor did we mean to even suggest that the prosecutor was barred from trying to show in any fashion that a witness’ testimony was not influenced by the immunized testimony.3
What we did insist upon, however— and here we quite definitely part company with the Chief Judge — is that the prosecutor has to prove that witnesses who testified against the defendant did not draw upon the immunized testimony to use it against the defendant; the burden of disproving use cannot, under Kastigar, be shifted onto the defendant, nor can the defendant be required to assume the burden of going forward with evidence that puts in issue the question of use. Most important, the defendant is entitled to a hearing at which he would be able to challenge the prosecution’s case for non-use.
Although our dissenting colleague expresses concern over the special institutional interests of the Independent Counsel, she does not suggest, nor could it plausibly be suggested, that the defendant’s constitutional rights are somehow lessened because he was prosecuted by the Independent Counsel rather than a United States attorney or the criminal division of the Justice Department. Therefore, the dissent’s rationalization (truly post hoc) of the district judge’s refusal to put the IC to its proof at a hearing must apply to any case in which the defendant gave immunized public testimony to a congressional committee. The dissent’s focus is on executive branch misconduct, but congressional committees have held highly publicized hearings into a number of other perceived problems, like the influence of organized crime, corruption in the labor movement, dubious practices on Wall Street, and even, as some will recall, communist influence in Hollywood. We cannot imagine what subjects will be of public and thus congressional interest in the future. We must assume that any American could be compelled to testify in return for use immunity under 18 U.S.C. § 6005 (1988), which authorizes Congress to grant that immunity, even over protests of the prosecutor, independent or otherwise. And thus the novel approach suggested by our colleague would apply to any person who finds him or herself in the position of being prosecuted after having testified publicly before Congress.
The dissent argues that the district judge was not obliged to hold a hearing to determine whether or not the witnesses changed or shaped their testimony (or, for that matter, offered to testify) because of the immunized testimony. It is not because the question is irrelevant, according to the dissent, but rather because the IC produced something like “a prima facie case” that the witnesses’ testimony was not tainted. Dissent on Pet. for Reh’g at 954. We are rather puzzled because we do not perceive that the IC put on any evidence whatsoever *944directed to this issue. Indeed, the district judge (as did our colleague) relied on an in-chambers review, a sort of “self-directed ... inquiry,” Carducci v. Regan, 714 F.2d 171, 177 (D.C.Cir.1983), to satisfy himself that there was no taint. Of course, this “review” neatly avoided any cross-examination of witnesses who were admittedly exposed to the immunized testimony (which, coupled with the switch in testimony of one key witness, may be at the core of this dispute). Even if such a proceeding could substitute for an adversary hearing (which we think quite a remarkable proposition), it could not possibly do so in this case because the district judge believed that independent exposure can never violate Kasti-gar. See United States v. Poindexter, 698 F.Supp. 300, 307, 313-14 (D.D.C.1988). Therefore, his “preliminary” Kastigar finding, which the dissent describes as based on “a thorough reading of preliminary witness interviews and the grand jury record,” Dissent on Pet. for Reh’g at 955, seems not only inadequate, but quite beside the point as well.
If the prosecutor were to demonstrate through testimony that a particular witness exposed to the immunized testimony had not been affected by the exposure, for example, by showing that the witness had set down his story before exposure, then the burden of going forward would shift to the defendant to challenge that version. But the dissent constructs the “prima facie case” out of whole cloth by relying merely on the district court’s admonition to witnesses to testify based on personal knowledge,4 as if that satisfied the prosecutor’s Kastigar burden.
The IC (and the district court) obviously wished to avoid cross-examination of the exposed witnesses. Some might convincingly testify that their exposure had no effect on their trial or grand jury testimony. Others might well testify that they simply were unable to determine just how much exposure affected their testimony, in which case that uncertainty would surely be a grave problem for the party with the burden of proof — the prosecutor. In this case, however, we know that at least one crucial witness changed his testimony before Congress after hearing the immunized testimony, and then presumably told the modified version to the trial jury. If by some alchemy the burden of going forward at the outset were to be shifted to the defendant (which we think plainly impermissible), we find it impossible to understand why that undisputed showing alone would not satisfy that burden. Why does it not meet even our dissenting colleague’s requirement for a contradiction between testimony prior to exposure and testimony subsequent to exposure?5
When all is said and done, the district judge denied the defendant a hearing to which the Constitution entitled him. The Chief Judge’s new formulation of constitutional law does appear to justify that denial, but we think it does so only by subordinating the defendant’s constitutional rights to various other interests.
The premise of the Chief Judge’s position is that the federal courts must treat the issue of witness exposure quite differently from prosecution staff exposure because a federal prosecutor can control only the latter. We think it is a mistaken premise because, as we have noted, it does not *945matter to a defendant if his immunized testimony is used against him by a key witness (and his lawyer) rather than by the prosecutor. The damage to the defendant — which is the focus of Kastigar — is the same in either case.
In any event, although it is not an insignificant problem, we think the dissent exaggerates a prosecutor’s difficulties. We can think of a number of ways that a federal prosecutor could seek to prevent exposure of witnesses he or she may intend to use, and even more ways to memorialize a witness’ testimony before exposure. The dissent is apparently concerned about a witness hostile to the prosecution who deliberately exposes himself to the immunized testimony in order to destroy the value of his testimony. There is, of course, not a shred of evidence that the IC encountered this problem in this case. Indeed, only the Chief Judge raises this problem — not the IC and not the district judge. If a prosecutor had such a concern about a particular witness, that witness would be at the very top of the list of those whose testimony should be prerecorded. And if at a Kasti-gar hearing such a witness should seek to undermine the case, the prosecutor would be entitled to bring out such a motivation in his examination of the witness.
Our dissenting colleague points also to the particular problem faced by an Independent Counsel whose investigation is targeted against one or more executive branch officials. She suggests that other officials in the executive branch who could be called as witnesses might seek to frustrate the conviction of a target by exposing themselves to immunized testimony. That is actually less of a problem than it would be for an ordinary United States attorney targeting a non-government official. Government officials are subject to greater restraints on their behavior than private individuals. The Ethics in Government Act requires the Department of Justice to cooperate with an Independent Counsel. See 28 U.S.C. § 594(d) (1988). Other executive departments are expected to cooperate with the Department of Justice, the chief law enforcement arm of the executive. Moreover, the IC presumably has the power to bring charges of obstruction of justice against anyone who attempts to sabotage the investigation. We are not aware that the Independent Counsel made any efforts to prevent government officials who were to testify or who had already testified from exposing themselves to immunized testimony. The IC’s position, unlike the dissent’s, seems to have been that the matter was irrelevant or perhaps, after the exposure of the key witness and his modification of his testimony, that the horse was out of the barn.
Finally, and perhaps at the heart of the dissent’s concerns, is the argument that a straightforward application of Kastigar in cases where a witness testifies before Congress, after Congress grants immunity under section 6005, unduly restricts Congress’ role in exposing wrongdoing in the nation — including wrongdoing in the executive branch'. She even contends that witnesses who wished to frustrate prosecutors would “line up to testify before Congress[ ] in exchange for ... immunity.” Dissent on Pet. for Reh’g at 953. We do not think Congress would be so naive as lightly to grant use immunity to such prospective defendants. Surely Congress does so only when its perception of the national interest justifies this extraordinary step. When Congress grants immunity before the prosecution has completed preparing its “case,” the prosecutor, whoever that may be, can warn that the grant of immunity has its institutional costs; in this case, the IC indeed warned Congress that “any grant of use and derivative use immunity would create serious — and perhaps insurmountable— barriers to the prosecution of the immunized witness.” Memorandum of the Independent Counsel Concerning Use Immunity 1 (Jan. 13, 1987) (Submitted to the Joint Congressional Iran/Contra Committees) (J.A. at 2502). The decision as to whether the national interest justifies that institutional cost in the enforcement of the criminal laws is, of course, a political one to be made by Congress. Once made, however, that cost cannot be paid in the coin of a defendant’s constitutional rights. That is simply not the way our system works. The *946political needs of the majority, or Congress, or the President never, never, never, should trump an individual’s explicit constitutional protections. Indeed, the government may not even use immunized testimony to prevent a defendant’s subsequent perjury. See New Jersey v. Portash, 440 U.S. 450, 459, 99 S.Ct. 1292, 1297, 59 L.Ed.2d 501 (1979) (“Testimony given in response to a grant of legislative immunity is the essence of coerced testimony.... [In the case of immunized testimony,] we deal with the constitutional privilege against compulsory self-incrimination in its most pristine form. Balancing, therefore, is not simply unnecessary. It is impermissible.”).6
The Chief Judge tentatively suggests a post hoe doctrinal justification for the district court’s breach of the Kastigar “any use” wall, but, in doing so, we think she muddles two distinct concepts: (1) how one traces a causal connection between immunized testimony and grand jury or trial testimony to determine whether there is in fact “use,” and (2) who, if anyone, may “use” immunized testimony against a defendant. Of course, a ban on any use of immunized testimony requires the prosecution to prove that proffered evidence, which does not appear on its face to be drawn from immunized testimony, is not “directly or indirectly derived from such testimony.” 18 U.S.C. § 6002 (1988) (emphasis added). And that process also, of course, is focused on the presence or absence of causal links between the immunized testimony and the proffered testimony. That is a factual inquiry; indeed, it is the central purpose of a Kastigar hearing. In our case, for instance, the district judge might find that a particular witness’ exposure to immunized testimony was so peripheral — let us say he only saw a newspaper headline — that the judge could safely find that the witness’ testimony was not tainted by the exposure, and therefore there is, in that situation, no use of the immunized testimony against the defendant. It is in that context that prior Fourth Amendment and Fifth Amendment eases on causation discussed under the rubric “fruit of a poisonous tree” are arguably relevant.7 As should be quite apparent, however, the exploration of these causation issues demands a Kastigar hearing. Instead, the dissent asks us to permit the district court to wave a wand of benedic*947tion over boxes of documents and proclaim a factual finding. But absolutely nothing in the Chief Judge’s discussion of Fourth and Fifth Amendment causation cases provides support for assuming non-causation as a matter of law or for affirming on appeal findings made or implied without a hearing, on the mere supposition that these actual or implicit findings must have been based on the totality of the evidence before the district judge.
In any event, causation is not the central issue in this case, and therein lies the Chief Judge’s muddle. It would seem that witnesses who appeared before the grand jury and trial jury actually studied North’s testimony. It is hard to imagine a more direct use of immunized testimony than in such a situation, and therefore the dissent’s use of the phrase “attenuated use” seems quite inappropriate. We take it that the Chief Judge means to imply that such direct use is somehow “attenuated” if it does not bear the prosecutor’s fingerprints, but that is simply another way of putting her main argument, that Kastigar’s protection can be easily evaded so long as an actor, independent of the prosecutor, does the damage to the defendant. None of the cases cited and discussed by the Chief Judge provides a shred of support for that proposition.
II. Immunized Testimony Before the Grand Jury
The IC renews its argument that presentation of immunized testimony to the grand jury is permissible and that no inquiry into whether the grand jury considered evi-denee based upon North’s congressional testimony is therefore appropriate. The IC cites a long line of cases from both the Supreme Court and this court as having decided that a “defendant who has been compelled to incriminate himself” is entitled only to have that evidence suppressed at trial and not to have it excluded from consideration by the grand jury. Pet. for Reh’g at 10 & n. 9. But the IC fails to note that we have previously held that the grand jury may not consider immunized testimony or evidence derived from it. See Rinaldi, 808 F.2d at 1582-83. We therefore adhere to our original disposition; however, because neither our original opinion nor our opinion in Rinaldi discussed the line of authority now relied upon by the IC, we offer the following additional thoughts.
Under the IC’s view, these cases stand for the proposition that a prosecutor could, consistent with Kastigar, read compelled testimony verbatim to the grand jury. All of the cases the IC cites, however, involve the presentation to the grand jury of evidence previously obtained in violation of a defendant’s privilege against self-incrimination;8 none involves grand jury consideration of testimony obtained from the defendant through a grant of immunity. The IC thus continues to miss the fundamental distinction between the presentation to the grand jury of evidence that has previously been unconstitutionally obtained and that of constitutionally-obtained evidence whose exposure to the grand jury amounts to a constitutional violation in and of itself.
*948As we recently recognized, “[gjrand jury inquiries grounded on information obtained in violation of a constitutional provision do not themselves work an additional wrong; they ‘are only a derivative use of the product of a past unlawful [action].’ ” In re Sealed Case, 877 F.2d 976, 982 (D.C.Cir.1989) (quoting United States v. Calandra, 414 U.S. 338, 354, 94 S.Ct. 613, 623, 38 L.Ed.2d 561 (1974)). And “[w]hether such derivative use of illegally obtained evidence by a grand jury should be proscribed presents a question, not of rights, but of remedies.” Calandra, 414 U.S. at 354, 94 S.Ct. at 623. By contrast, the grand jury and the grand jury process may never “itself violate a valid privilege”; such action presents a question not of remedies but of rights. Id. at 346, 94 S.Ct. at 619 (“Although ... an indictment based on evidence obtained in violation of defendant’s Fifth Amendment privilege is nevertheless valid [citation omitted], the grand jury may not force a witness to answer questions in violation of that constitutional guarantee.”).
We believe — as do five of our sister circuits, see Maj.Op. at 869-870 — that grand jury consideration of evidence already unconstitutionally compelled and grand jury consideration of immunized testimony fall on different sides of this fence. In the former context, such as where Miranda warnings are not given, the constitutional violation occurs independent of the grand jury. Whether the resulting confession can be used derivatively by the grand jury or in subsequent proceedings is a matter of the reach of the exclusionary rule, which is a function not of any rights of the defendant but of a remedial balance factoring in the possible unreliability of the confession and the need to deter the government from future violations of Fifth Amendment rights. See, e.g., Oregon v. Elstad, 470 U.S. 298, 304-08, 105 S.Ct. 1285, 1290-93, 84 L.Ed.2d 222 (1985); New York v. Quarles, 467 U.S. 649, 654, 104 S.Ct. 2626, 2630, 81 L.Ed.2d 550 (1984); Michigan v. Tucker, 417 U.S. 433, 445-47, 94 S.Ct. 2357, 2364-65, 41 L.Ed.2d 182 (1974). The exclusionary rule is, of course, by no means talismanic — where the goals of trustworthiness and deterrence are not implicated, the confession may be used. For example, a confession obtained in violation of Miranda may (provided it is trustworthy) be used to impeach the defendant’s contrary testimony at trial because “sufficient deterrence flows when the evidence in question is made unavailable to the prosecution in its case in chief.” Harris v. New York, 401 U.S. 222, 224-25, 91 S.Ct. 643, 645-46, 28 L.Ed.2d 1 (1971). The cases cited by the IC thus reflect only the familiar proposition that, while evidence obtained previously in violation of the defendant’s Fifth Amendment privilege may not be used by the prosecution in its case in chief at trial, it may be used for other purposes, including grand jury proceedings.
In contrast, as the Supreme Court has recognized, use of immunized testimony is never justified by such balancing considerations. See Portash, 440 U.S. at 459, 99 S.Ct. at 1297. The prosecution obtains the immunized testimony legally, but only by promising that neither the testimony or information itself nor any information directly or indirectly derived from it will “be used against [the defendant] in any criminal case.” 18 U.S.C. § 6002. And it is only this promise that compels the defendant to testify in spite of his constitutional privilege: “immunity from use and derivative use is coextensive with the scope of the privilege against self-incrimination.... [because i]t prohibits the prosecutorial authorities from using the compelled testimony in any respect.” Kastigar, 406 U.S. at 453, 92 S.Ct. at 1661 (emphasis in original). When the prosecution reneges on this constitutionally-mandated bargain and presents the immunized testimony to the grand jury, the constitutional violation is part and parcel of the grand jury process. The presentation — “use”—of the testimony is precisely the proscribed act. The issue is thus not one of "derivative use ... by the grand jury” and of the exclusionary rule (indeed, any use of the testimony is per se excluded under the statute and Kastigar). Rather, the situation is no different than if the grand jury had itself forced the defen*949dant to give incriminating answers and any indictment based upon immunized evidence is no less tainted.9
III. Count 9 Authorization Instructions
The IC is barred from arguing that we erred in construing 18 U.S.C. § 2071(b) to require that a defendant possess “knowledge of unlawfulness.” Maj.Op. at 886. Despite its current protestations to the contrary, the IC never made, and thus waived, this argument. At no point in its brief did the IC dispute North’s contention that “knowledge of unlawfulness” is a required element of this statute. North's reply brief emphasized that knowledge of unlawfulness meant actual knowledge, citing two cases in support — including United States v. Cullen, 454 F.2d 386 (7th Cir.1971), on which the IC now relies.10 As a result, at oral argument both the court and North’s counsel understood the question to be uncontested. The following dialogue took place during the opening argument of North’s counsel.
QUESTION: Wait a minute. Knowledge of unlawfulness, it is agreed by both parties, is required under Count 9, not under Count 6. Is that correct?
MR. SIMON: That’s correct, Your Hon- or, and in pointing out problems with the counts, there is no problem. It is absolutely clear that Count 9, the other count that I did want to address briefly, Count 9, those instructions clearly require reversal as to Count 9, because the instructions are undisputed that the law requires knowledge of unlawfulness.
Tr. at 37. If the IC had remained silent on this issue at oral argument we would surely have been entitled to assume that it had waived the contention it now raises, but the IC, in response, expressly conceded the point.
QUESTION: I am inclined to think you are correct that [Count 6] does not require knowledge of unlawfulness, as Count 9 does and you concede. And I think you say in your brief, and I think you are correct, that it requires at least knowledge of wrongfulness. Is that correct?
MR. LYNCH: Yes.
Tr. at 73 (emphasis added).11
The revisionist nature of the IC’s current claim is further illustrated by its new found reliance in its petition for rehearing on dictum in Cullen, 454 F.2d at 392, which, according to the IC, conflicts with our view of the requisite mens rea. The IC did not cite Cullen in its brief or mention it at argument, as it surely would have done had it meant to raise the point it now argues. Thus, the IC never asserted in these extensive proceedings — until its petition for rehearing — that the test of 18 U.S.C. § 2071(b), the statutory section alleged to be violated in Count 9, could be satisfied by the government if it showed that a defendant should have known, in accordance with an objective test, that his conduct was unlawful. Indeed, Chief Judge Wald, who dissented from our origi*950nal opinion, did not then dispute our characterization of the IC’s argument as having agreed (or conceded) that actual knowledge of unlawfulness was required under Count 9. Compare Maj.Op. at 884-886 with Diss.Op. at 929, 930-932.
To be sure, Judge Ruth B. Ginsburg, dissenting from the denial of rehearing en banc on this Count alone, asserts that, notwithstanding all of the above, the IC did preserve in its brief the argument it now makes. She quotes from page 39 of the IC’s brief: “But an unreasonable belief that an order to lie to Congress or alter official records made such conduct legal no more negates guilt than would an unreasonable belief that the conduct itself had not been prohibited.” The difficulty with this sentence, however, which is not specifically directed at Count 9, is that the same conduct was also alleged in Count 6 as violating § 1505 and the IC did argue that it was not obliged to prove knowledge of unlawfulness as to Count 6. At no point in the IC’s brief does the IC claim that it was not required to prove actual knowledge of unlawfulness to make out the violation of § 2071, charged in Count 9. The closest the IC comes to that argument is its carefully crafted footnote 73 in which it claims that “North cites no case holding that the state of mind required for violation of either § 1505 or § 2071 is precluded by an unreasonable belief that the conduct was authorized.” We note that the sentence purposefully does not affirmatively argue the contrary. Authorization, moreover, is not necessarily the equivalent of lawfulness. The petition for rehearing clearly makes the new and broader argument that even if North believed (reasonably or not) that his conduct was authorized, he can still be convicted under Count 9 — requiring the government to prove knowledge of unlawfulness — if his reliance on authorization to avoid illegality was unreasonable. The IC’s brief avoided any analysis of the mental state required under § 2071; footnote 73 glosses over that issue, eliding it with the mental state required by § 1505.
In short, Judge Ruth B. Ginsburg’s differing reading notwithstanding, it appears to us that for whatever reason (perhaps the lack of any supporting authority), the IC deliberately chose not to make the argument it now raises for the first time. We therefore believe that the IC’s contention upon which it rests its petition for rehearing — that the panel “[erroneously claim[ed] that the Government agreed that ... 18 U.S.C. § 2071(b) ‘requires subjective knowledge of unlawfulness for conviction,’ ” Pet. for Reh’g at 12 (quoting Maj.Op. at 886) — is a misstatement. In any event, we cannot imagine that this issue is en banc worthy in accordance with any of the principles that govern such determinations. We disagree with Judge Ruth B. Ginsburg’s characterization of our reasoning in the case that was before us, which, after all, relies in part on a prior decision of this court. See United States v. Rhone, 864 F.2d 832, 835 (D.C.Cir.1989). The petition for rehearing, however, is based, not on a disagreement with the reasoning we employed in the case we decided, but rather on the new theory, previously disavowed, presented in the petition. Although we decline to entertain this revisionist argument at this late stage in the proceeding (whatever its merit or lack thereof), we do not see how the government (or the IC) could be barred from raising the argument in another case. So, on the assumption that the IC should not be treated any differently from other litigants before the court, we do not understand how it can be thought that its new claim is en banc worthy.
IV. Jury Unanimity Instruction
As to the IC’s final point — that no specific unanimity instruction was required as to Count 9 — upon reviewing the petition, the response of North, and the instructions of the district court to the jury, we conclude that this point is well taken. This Count of the indictment “charged that North, having custody of NSC documents, ‘willfully and knowingly did conceal, remove, mutilate, obliterate, falsify and destroy and did cause to be concealed, removed, mutilated, obliterated, falsified and destroyed records, papers and documents *951filed and deposited in a public office....”’ United States v. North, Maj.Op. at 876, quoting Joint Appendix at 260-61. As originally conceived, Count 9 concerned North’s handling of at least three groups of documents in several distinct incidents. At the time of the issuance of our original opinion, both the majority opinion (Maj.Op. at 876-877) and the dissent (Dissent at 925) failed to note that the district court had instructed the jury to limit its consideration to a single incident involving five specific documents. Therefore, each opinion dealt with the question as if all documents and incidents originally charged in the indictment were still before the jury.
The IC in his motion for reconsideration called our attention to the trial court’s limiting instruction. We now review the instruction including the limitation under the principle that these instructions must be considered “as a whole.” United States v. Mangieri, 694 F.2d 1270, 1280 (D.C.Cir.1982). Having done so, we conclude that the instructions on Count 9 as a whole did not pose “a genuine risk that the jury [would be] confused.” United States v. Duncan, 850 F.2d 1104, 1114 (6th Cir.1988), cert. denied, _ U.S. _, 110 S.Ct. 732, 107 L.Ed.2d 751 (1990). As the IC argues in his petition for rehearing, “[t]he evidence was identical as to all five documents ... [t]hus, the jury was restricted to one continuous course of events. United States v. North, 716 F.Supp. 644, 649 (D.D.C.1989).” Thus, the omission of a specific unanimity instruction did not constitute reversible error. We will therefore allow the petition of the Independent Counsel to this limited extent, and withdraw Section II of our prior opinion herein.
. Three of our sister circuits require that the government prove that a witness was not motivated to testify by exposure to immunized testimony. See United States v. Brimberry, 803 F.2d 908, 915-17 (7th Cir.1986), cert. denied, 481 U.S. 1039, 107 S.Ct. 1977, 95 L.Ed.2d 817 (1987); United States v. Hampton, 775 F.2d 1479, 1489 (11th Cir.1985); United States v. Kurzer, 534 F.2d 511, 517-18 (2d Cir.1976). And we know that North's immunized testimony motivated one witness, Robert C. McFarlane, to expand upon his testimony. See Maj.Op. at 864-865.
. We frankly do not understand why the Chief Judge would wish to read our opinion now — as she did not do in her earlier dissent — in such a restrictive and unnatural way, turning a "may” into a "must.” Dissent on Pet. for Reh’g at 2-3. Nor do we comprehend why the dissent would wish us to set down "guidelines” to control how the parties might litigate this issue when such guidelines would, in effect, decide questions not before us and would represent “an unneeded and unprecedented incursion into the trial court’s discretion." Dissent on Pet. for Reh’g at 956.
. Chief Judge Wald describes Rinaldi as standing only for a rule of "inevitable discovery," i.e., that if the prosecutor would have inevitably come upon certain information from a particular witness, it matters not if the witness’ testimony before the grand jury was shaped by the immunized testimony. Rinaldi, however, was focused at least with respect to that witness only on the question whether facts presented to the grand jury were independently gathered, not the issue with which we are confronted — whether the witness' testimony was shaped and influenced by exposure. Indeed, our dissenting colleague appears to concede that Kastigar bars the use of a witness whose testimony is so shaped.
. We note that, if such instructions were a sufficient safeguard, there would be no need for the rule requiring a district court, at the request of a party, to exclude witnesses from the courtroom so that they cannot hear — and have their testimony shaped by — the testimony of other witnesses. See Fed.R.Evid. 615.
. We think that the dissent’s analysis of the difficulty with the McFarlane testimony is flawed. That McFarlane changed his congressional testimony in response to North’s immunized testimony implicates far more than his "credibility." Dissent on Pet. for Reh’g at 955 n. 3. It poses the crucial question whether the changed congressional testimony influenced, indeed, was reflected in his trial testimony. It is irrelevant whether McFarlane’s testimony before the grand jury, given before the defendant's immunized testimony in front of Congress, was not itself inconsistent with McFarlane's testimony at trial. The issue is whether McFarlane testified at trial in such a way as to incorporate any of his revised testimony before Congress. In any event, we have before us only the district judge’s assertion as to the comparison of the grand jury and trial testimony, not a finding based on record evidence.
. Contrary to our colleague’s assertion that use immunity "exists in a delicate tension with the Fifth Amendment,” and her accusation that we have "upset this tension,” Dissent on Pet. for Reh’g at 951, the Fifth Amendment defines the parameters and limits the scope of any form of statutory immunity. The Supreme Court framed the issue of the constitutionality of 18 U.S.C. § 6002 in precisely these terms: "The constitutional inquiry, rooted in logic and history, as well as in the decisions of this Court, is whether the immunity granted under this statute is coextensive with the scope of the privilege." Kastigar, 406 U.S. at 449, 92 S.Ct. at 1659 (footnote omitted). The Court upheld the constitutionality of the use immunity statute only because the statute was construed as providing "substantial protection, commensurate with that resulting from invoking the privilege itself.” Id. at 461, 92 S.Ct. at 1665.
. The fruit of the poisonous tree metaphor is actually backwards as applied to a Kastigar problem. The "tree” — the immunized testimony — is not poisonous; it is perfectly legal and only turns poisonous when used against the defendant. This suggests that the causation analysis will prove to be somewhat different in an immunity case than in determining whether evidence is a fruit of a Fourth or Fifth Amendment violation. See, e.g., United States v. Kurzer, 534 F.2d 511, 516 (2d Cir.1976). For instance, all the cases cited by the Chief Judge involve situations where an "independent act of free will” by the defendant (a voluntary confession by which the defendant waived his Fifth Amendment privilege) broke the chain of causation leading from a constitutional violation. See, e.g., Wong Sun v. United States, 371 U.S. 471, 487-88, 83 S.Ct. 407, 417-18, 9 L.Ed.2d 441 (1963); Pillsbury Co. v. Conboy, 459 U.S. 248, 280, 103 S.Ct. 608, 625, 74 L.Ed.2d 430 (1983) (Blackmun, J., concurring in the judgment); see also United States v. Bayer, 331 U.S. 532, 540-41, 67 S.Ct. 1394, 1398-99, 91 L.Ed. 1654 (1947). This analysis obviously has little applicability in the typical immunity case, where the defendant asserts his Fifth Amendment privilege at every opportunity and commits no independent, intervening act that breaks the chain leading from his compelled testimony to any use of it before the grand jury or at trial. And, of course, this focus on subsequent, voluntary waiver is not the same as saying, as the dissent claims, that the link between the constitutional violation and the evidence is too elongated or circuitous to be constitutionally relevant. Cf. United States v. Crews, 445 U.S. 463, 471, 100 S.Ct. 1244, 1249, 63 L.Ed.2d 537 (1980).
. See, e.g., United States v. Blue, 384 U.S. 251, 255, 86 S.Ct. 1416, 1419, 16 L.Ed.2d 510 (1966) (incriminating evidence previously filed by the defendant in a tax deficiency proceeding before the Tax Court could be considered by a grand jury investigating related criminal tax evasion charges “[e]ven if we assume that the Government did acquire [the] evidence in violation of the Fifth Amendment”); Lawn v. United States, 355 U.S. 339, 345-50, 78 S.Ct. 311, 315-18, 2 L.Ed.2d 321 (1958) (incriminating evidence obtained from a defendant who had not been apprised of his Fifth Amendment rights could be considered by a subsequent grand jury); Holt v. United States, 218 U.S. 245, 247-48, 31 S.Ct. 2, 4-5, 54 L.Ed. 1021 (1910) (coerced or “incompetent” confession could be considered by a grand jury); see also Midland Asphalt Corp. v. United States, 489 U.S. 794, 800, 109 S.Ct. 1494, 1499, 103 L.Ed.2d 879 (1989) (citing Lawn, supra, for the proposition that "we have held that even the grand jury’s violation of the defendant’s right against self-incrimination does not trigger the Grand Jury Clause’s 'right not to be tried’ ”); In re Sealed Case, 877 F.2d 976, 981-82 (D.C.Cir.1989) (evidence obtained by the government in violation of the defendant’s attorney-client privilege could be considered by the grand jury); Laughlin v. United States, 385 F.2d 287, 291 (D.C.Cir.1967), cert. denied, 390 U.S. 1003, 88 S.Ct. 1245, 20 L.Ed.2d 103 (1968) (conversation recorded in violation of the Fourth Amendment could be presented to the grand jury).
. Of course, to be entitled to a hearing on whether immunized testimony was before the grand jury, a defendant must lay a firm "foundation” resting on more than “suspicion” that this may in fact have happened. Cf. Lawn, 355 U.S. at 348-49, 78 S.Ct. at 317-18. In light of the district court’s finding that grand jury witnesses were exposed to his immunized testimony, see Maj. Op. at 866-867, North has clearly met this burden.
. Cullen's holding, as opposed to its dicta, supports North. In discussing the jury instructions, the Seventh Circuit observed that "[t]he Government recognizes, and the judge’s instructions plainly stated, that knowledge of illegality was an element of each of the offenses committed by appellant.” Cullen, 454 F.2d at 391. The assertion upon which the IC relies — that conviction could be sustained if the defendant "reasonably should have known” that his conduct is wrongful, id. at 392 — comes as dictum because Cullen knew that he was breaking the law.
. On occasion counsel can be “momentarily caught off guard by the court’s vigorous questioning,” Church of Scientology v. IRS, 792 F.2d 153, 171 n. 10 (D.C.Cir.1986) (en banc) (Silberman, J., concurring), aff’d, 484 U.S. 9, 108 S.Ct. 271, 98 L.Ed.2d 228 (1987), but we are quite certain that it did not happen in this case. Mr. Lynch, who is as able an appellate advocate as we have ever observed, seems to us to have known precisely what he was saying. And we doubt that Mr. Lynch, whose name does not appear on the petition for rehearing, would expect any special solicitude from this court.