dissenting:
The majority has written a well reasoned opinion on the scope of formal statutory immunity. Insofar as the court holds that under a formal grant of immunity, an individual is shielded from prosecution only to the extent of his Fifth Amendment privilege, I believe it correctly states the law. Unfortunately, this case does not involve formal statutory immunity. Instead, this case involves an agreement between the defendant and the prosecutor in which the prosecutor agreed not to prosecute the defendant in return for his cooperation. Not only does the majority fail to recognize the fundamental difference between the two forms of immunity, it assumes that the same rules apply to formal and informal immunity. Since the same principles do not apply, I dissent. To understand why the analysis of the majority is erroneous, it is necessary to understand the various forms of “immunity.” Only with that understanding it is possible to apply the correct analysis to the case at hand.
I
In two key sections, the majority states that the same rules apply to formal and informal immunity. Supra at 1444, 1446. Specifically the majority holds that the scope of any grant of immunity is defined by the Fifth Amendment. Before explaining this error, it is necessary to understand the difference between transactional and use immunity as well as the difference between formal and informal immunity. Transactional immunity “accords full immunity from prosecution for the offense to which the compelled testimony relates.” Kastigar v. United States, 406 U.S. 441, 453, 92 S.Ct. 1653, 1661, 32 L.Ed.2d 212 (1972). Use immunity, on the other hand, is more limited; it protects the individual from prosecution through the use of the immunized testimony or evidence derived from that testimony. Therefore, while transactional immunity prohibits any future prosecution, use immunity only limits the government’s manner of proof in a subsequent prosecution. This distinction is significant in this case because the magistrate found that the government granted Harvey “transactional immunity” or full immunity from prosecution. As the majority correctly states, the issue in this case is the scope of that “transactional immunity.” The majority holds that the scope is coextensive with the Fifth Amendment privilege. To understand why the majority is incorrect, it is necessary to understand the distinction between formal and informal immunity. Because the two forms of immunity come from different sources, the scope of each type of immunity differs.
Formal or statutory immunity is set out in 18 U.S.C. § 6001 et seq. Immunity is granted by a court upon the U.S. Attorney’s request when a witness refuses to testify before a grand jury or at trial based *1450on his Fifth Amendment privilege ‘against self-incrimination. 18 U.S.C. § 6003(a). The statute authorizes the granting of “use” and derivative use immunity. 18 U.S.C. § 6002. Several points are noteworthy. First, a United States Attorney does not have the power to grant formal immunity. Instead, he must first subpoena a witness and if the witness invokes the Fifth Amendment privilege, the prosecutor must obtain approval by the Attorney General or Deputy Attorney General and then request the court to order the witness to testify. 18 U.S.C. § 6003.1 Second, the statute only authorizes use immunity, not transactional immunity. Third, since formal immunity is granted to overcome a witness’ invocation of the Fifth Amendment, the Supreme Court has held that the scope of the immunity granted must be as broad as the privilege. Kastigar, 406 U.S. at 450, 92 S.Ct. at 1659.
Due to the cumbersome requirements of obtaining properly authorized statutory immunity, U.S. Attorneys often make informal agreements with individuals in return for their cooperation. See United States v. Quatermain, 613 F.2d 38, 45 (3d Cir.) (Aldisert, J., dissenting), cert. denied, 446 U.S. 954, 100 S.Ct. 2923, 64 L.Ed.2d 812 (1980). The agreements are perfectly analogous to plea agreements: an individual with valuable information bargains with the prosecutor with respect to pending charges in return for that individual’s cooperation. A usual condition of cooperation is that the individual not be subject to prosecution for any of the information he provides. See id. A prosecutor’s power to grant informal immunity derives from his inherent discretion over prosecuting cases; just as a prosecutor has the discretion to plea bargain, he has the discretion to grant an individual immunity from prosecution. We have held that “due process requires the prosecutor’s promise to be fulfilled.” Rowe v. Griffin, 676 F.2d 524, 528 (11th Cir.1982); see also Plaster v. United States, 789 F.2d 289, 293 (4th Cir.1986); United States v. Fountain, 776 F.2d 878, 882 (10th Cir.1985); United States v. Carter, 454 F.2d 426, 428 (4th Cir.1972).
This practice has been dubbed “informal immunity,” “hip pocket immunity,” see Quatermain, 613 F.2d at 45, or “equitable immunity.” Rowe, 676 F.2d at 526. Additionally, since the prosecutor often agrees not to prosecute at all, these agreements are sometimes carelessly labeled “transactional immunity.” See Rowe, 676 F.2d at 526 (since prosecutor promised Rowe there would be no subsequent prosecution, court stated he was offered “transactional immunity”). All these terms are unfortunate misnomers because they lead to confusion with formal statutory immunity. Such confusion ignores the fact that the two types of immunity derive from totally different sources and that the source of the immunity determines the scope of a specific grant of immunity. For example, 18 U.S.C. § 6002 only authorizes use immunity. More importantly, because statutory immunity is granted to avoid reliance on the Fifth Amendment privilege, the scope of immunity must be coextensive with the Fifth Amendment privilege. The Fifth Amendment only protects an individual against divulging information about future conduct if he faced a substantial risk of incrimination as to those events at the time. See United States v. Freed, 401 U.S. 601, 603, 91 S.Ct. 1112, 1115, 28 L.Ed.2d 356 (1971) (firearm registration requirement did not violate Fifth Amendment); Marchetti v. United States, 390 U.S. 39, 53, 88 S.Ct. 697, 705, 19 L.Ed.2d 889 (1968) (tax registration requirements violated fifth amendment because registrants could expect provisions to serve as evidence of violation of gambling laws). It therefore follows that under a formal grant of immunity, a witness is only immunized with respect to conduct if he faced a substantial risk of incrimination as to those events when he testified.
In cases of informal immunity, however, the scope of the immunity is not limited by *1451the Fifth Amendment. As Judge Fay has pointed out,
under the self-incrimination clause of the fifth amendment, evidence of guilt induced by a government promise of immunity is ‘coerced’ evidence and may not be used against the accused. For purposes of compelling testimony which otherwise would be privileged by the fifth amendment, all that is constitutionally required is a grant of use immunity. However, in order to secure testimony, evidence or other cooperation from a potential criminal defendant, a prosecutor may see fit to promise complete immunity from prosecution.
Rowe, 676 F.2d at 527 (emphasis added). Rowe holds that the government must offer at least use immunity when an individual is induced to cooperate, but that there is no limit to what the defendant can demand in return for his cooperation. See Quater-main, 613 F.2d at 45 (Aldisert, J., dissenting) (“[T]he United States Attorney is at liberty to impose conditions that usually relate to testifying or providing certain information. For his part the ... informant often imposes conditions of his own, usually relating to agreements not to prosecute but often covering other matters as well[.]”). If the potential informant demands too much, the government may decide that the information is not worth the price or the government can always subpoena the potential informant to testify before a grand jury or at the trial thereby ensuring that the informant is only granted use immunity. This discussion illustrates that the scope of an informal grant of immunity depends on the bargain struck.
The majority therefore is incorrect to assume the same principles apply to determining the scope of formal and informal immunity. In determining that the Fifth Amendment defines the scope of a grant of informal immunity, the majority ignores the cited quotation from Rowe. The only case the majority cites as support for its conclusion is United States v. Quatermain, 613 F.2d 38 (3d Cir.1984). Unfortunately, in Quatermain, the court specifically held that the informant was granted “the minimum immunity required by the Constitution” — that is, use immunity. Id. at 38 (emphasis added). Therefore, the fact that the agreement provides use immunity made the Fifth Amendment case law relevant, not the fact that it was an informal grant of immunity.
Rowe provides the appropriate analysis to apply in cases of informal immunity. In Rowe, the court considered a prosecutor’s agreement not to prosecute a Ku Klux Klan informant in return for the information he provided the state concerning a murder during the Selma to Montgomery Civil Rights March. 676 F.2d at 525.2 The court held that such an agreement must be enforced when the defendant proves that an agreement was made, that he performed his side and that the prosecution was directly related to the assistance the defendant had given. The court specifically analogized to the case law on plea agreements and held that “as a matter of fair conduct, the government [must] honor such an agreement[.]” Id. at 527.
It follows then that the case law concerning the interpretation of plea agreements is relevant to the interpretation of this type of an agreement made by the prosecutor. See id. at 528 (“this contractual analysis applies equally well to promises of immunity from prosecution”). This court interprets a plea agreement consistently with what the defendant reasonably understood when he entered the plea. In re Arnett, 804 F.2d 1200, 1201-02 (11th Cir.1986). The court first determines whether the written agreement is ambiguous on its face. If the agreement is unambiguous and there is no allegation of government overreaching, the court will enforce the agreement according to its plain words. United States v. (Michael) Harvey, 791 F.2d 294, 300 (4th Cir.1986). If the agree*1452ment is ambiguous, the ambiguity ‘^should be resolved in favor of the criminal defendant.” Rowe, 676 F.2d at 526 n. 4 (ambiguity over whether Attorney General’s promise bound future Attorney General was resolved in favor of the defendant); see In re Arnett, 804 F.2d at 1203 (government breached the agreement when it sought forfeiture of defendant’s farm since written agreement ambiguous as to whether government would seek forfeiture of property and government could not satisfy heavy burden of proving defendant understood government reserved right to seek property forfeiture): United States v. (Michael) Harvey, 791 F.2d at 301 (imprecision in terms of written agreement construed against the government).
II
In this case, Harvey was not granted formal statutory immunity. He was never called to testify and never invoked his Fifth Amendment privilege. If he had been granted statutory immunity, a discussion of the scope of Harvey’s Fifth Amendment privilege would be relevant. Instead, Harvey bargained with the government. In return for the information he provided, the government agreed to drop the charges against him in Mobile and agreed not to prosecute him for any crimes related to the information he gave. There is no doubt that Harvey entered an agreement with the government and that he performed his side. The crux of this case, therefore, depends on an interpretation of the agreement not to prosecute.
The magistrate reconstructed the agreement and found that Harvey had been granted both “transactional” and “use” immunity for the information he provided. The magistrate also determined that Harvey had told the government about the Cayman Islands funds. The majority apparently takes comfort from this finding, stating “we are working solely with the familiar categories of transactional and use immunity, and do not face any different ‘species’ of immunity — e.g., an express agreement not to prosecute for future tax violations with respect to the Cayman Islands.” Supra at 1446 n. 10. Indeed as I read the majority opinion, its holding that Harvey’s immunity is only as broad as the fifth amendment is explicitly dependent on this factual finding. See supra at 1446 (“By the same token, we believe that — absent any contrary factual finding — we should not conclude that the scope of the immunity Harvey received was any greater than that of the fifth amendment privilege he gave up.”) (Emphasis added). I find this statement incomprehensible since the only “species of immunity” the prosecutor was authorized, to grant was an agreement not to prosecute. Additionally, the magistrate’s use of the terms “transactional” and “use” immunity should not be given such great weight since the term “transactional” immunity has been used by this court to describe an agreement not to prosecute. See Rowe, 676 F.2d at 526; Quatermain, 613 F.2d at 44 (Aldisert, J., dissenting) (although the district court phrased its discussion in terms of transactional and use immunity, analyzing it as an agreement not to prosecute leads to same result). Furthermore, it is clear from the magistrate’s opinion that although she used the terms “transactional” and “use” immunity, she understood the critical distinction between formal and informal immunity. In rejecting the government’s argument that it had no power to grant “transactional” immunity, the magistrate held
what the government confuses with respect to immunity is the court’s power under 18 U.S.C. 6001 et seq. to force an unwilling defendant to testify versus the government’s virtually unbridled discretion to plea bargain with any defendant as to terms offered by the government. With respect to § 6001 immunity, the court can compel a defendant to testify, but can only grant him use and not transactional immunity. On the other hand, the executive branch can grant transactional immunity in the form of a bargain and does not need the blessing of the court to do so.
Record, Yol. 3, Tab 72 at 22. Indeed, the magistrate applied the principles applicable to plea agreements to what she described “transactional” immunity. Therefore, de*1453spite the majority’s wishful thinking, we are dealing with an agreement not to prosecute.
In this case, the government never wrote down the terms of the agreement. Additionally, there is no record of the information Harvey provided. Clearly the written terms of the agreement would be the starting place for determining the scope of immunity Harvey was granted. Due to the government’s gross negligence, however, we are forced to reconstruct the terms of the agreement.3 In order to do so, the court must look to the testimony of those involved in negotiating the agreement to determine what Harvey believed the agreement provided and whether Harvey’s expectations were reasonable.
Jerry Harvey testified that the government “agreed nothing I ever give [sic] them would be used against me, nor would any U.S. Attorney’s Office seek to prosecute me for anything; that I was just getting a clean walk, and I should stay on the Government’s side and help them.” Record Vol. 3, Tab 72 at 14. Harvey’s attorney, Tom Haas, testified that “the understanding I had with [the government] was that nothing that Jerry Harvey said to them, or any agent on the Government would ever at any time be used against Jerry Harvey.” Id. at 15. This testimony supports Harvey’s argument that he believed he was immune from any prosecution related to the information he gave. Significantly, no testimony by either of the prosecutors involved in the negotiations rebutted Harvey’s broad interpretation of the agreement. In response to a question by the court, the U.S. Attorney for the Southern District of Alabama, William Kimbrough, testified that Harvey was given use , immunity but that he did not know whether or not he was given transactional immunity. Finally, the prosecutor most intimately involved with the agreement, Patrick Sullivan, an Assistant U.S. Attorney in the Southern District of Florida had no recollection of any involvement with Jerry Lee Harvey.4 He could not remember speaking to the Mobile U.S. Attorney’s office or having any negotiations with Harvey.
The court must interpret an agreement consistently with the defendant’s reasonable interpretation of the agreement. In this case, the government has failed to offer any evidence to disbelieve Harvey’s view of the agreement. Instead, the government argues that it was unreasonable for Harvey to believe that the agreement would shield him from prosecution for future tax violations relating to the Cayman Islands funds. I do not agree. It is not at all clear that a lay citizen would understand that a government’s agreement not to prosecute for anything related to the Cayman Islands funds would not preclude prosecution for failure to declare interest from those funds. In addition, since we have no record of the agreement we have no way of knowing what the government officials represented to Harvey as the terms of the agreement. In the absence of some evidence that Harvey knew the agreement would not cover these crimes,5 I cannot accept the government’s position. See (Michael) Harvey, 791 F.2d at 300 (due process requires holding government to a greater degree of responsibility for ambiguity in plea agreement than defendant). Furthermore, to the extent that the government’s argument is based on the belief the *1454government had no authority to enter the agreement as Harvey perceived it because it granted immunity for future crimes, it is not persuasive. First, it is not apparent that Harvey would know that the government did not have the power to enter the agreement as he perceived it. Second, that argument ignores the possibility that the government may have lead Harvey to believe (or at least contributed to his misunderstanding) that the agreement offered such immunity. Finally, this court has never refused to enforce a plea agreement just because the government made a bad deal.
I would therefore hold that the government agreed that it would not prosecute Harvey with respect to the Cayman Islands funds and that Harvey believed that he would not be prosecuted for failing to report the interest on the Cayman Islands funds. This does not mean that Harvey was immunized from declaring the interest. Quite the contrary, I believe that Harvey was required to pay taxes on the interest and that the government may collect those back taxes. It may not, however, criminally prosecute Harvey for failing to report his interest. I also do not believe that the agreement forever insulates Harvey from criminal prosecution for failing to report his taxes. Because the government failed to provide any evidence to disbelieve Harvey’s view of the agreement, it is apparent that the indictment entered against Harvey on November 25, 1985 for the first time put Harvey on notice that his understanding of the agreement conflicted with the government’s view. After that point, it became unreasonable for Harvey to believe the agreement provided such broad immunity.
Ill
In conclusion I wish to emphasize that this case presents unique facts and concerns which fortunately are of infrequent occurrence. The concern of the majority is that my view provides carte blanche authority to U.S. Attorneys to enter into plea agreements that will insulate criminals from liability for future criminal conduct. That concern has many answers, the chief of which is that U.S. Attorneys are responsible persons who do not conduct themselves as apprehended by the majority. I have tried to make clear that the holding is limited to the facts of this case. In this case, it was not unreasonable for Harvey to believe that the agreement covered the future tax consequences from the information he provided. Indeed, I have attached as an appendix excerpts from the testimony before the magistrate which show that the government may have interpreted the agreement to cover even more than this. I have also made clear that once Harvey was put on notice by the government that he was required to include income from the Cayman Island bank accounts on his income tax returns, he no longer could consider himself immune from prosecution for failure to report the income. Due process of law in the context of this case requires that Harvey be provided advance notice of the government’s interpretation of the agreement, especially if the government’s interpretation changed.
The majority contorts this simple case concerning an agreement not to prosecute into a use or transactional immunity case and then relies on irrelevant Fifth Amendment case authority. Here the same government that promised Harvey in a bona fide agreement that it would not seek to jail him based on information furnished in 1980 now seeks to breach that agreement. It must be remembered that the district court found: “that tainted evidence, evidence for which the defendant received both use and transactional immunity, was presented before the grand jury which returned the [tax evasion] indictment against him.”
The majority fears that if the government is required to abide by its contract, a pandora’s box will be opened where federal prosecutors will immunize criminals from being prosecuted for future crimes. That is obviously unreal. As I have explained, this case is an aberration. U.S. Attorneys seldom make oral agreements like this. We can have confidence that U.S. Attorneys will not abuse the informal method of granting immunity and presumably such agreements will be reduced to writing.
*1455Harvey’s due process rights not to be prosecuted pursuant to the government’s agreement are violated by the majority’s reversal of the district court’s dismissal of the tainted indictment.
APPENDIX
The following are excerpts from the magistrate’s report. (Record, Vol. 3, Tab 72).
Tom Haas [Harvey’s attorney] and William Kimbrough, who was at the time of the agreement the U.S. Attorney in the Southern District of Alabama, testified the deal negotiated with Harvey was that Harvey would not be prosecuted for anything about which he told the Government nor would anything he said be used against him.
* * * # * *
Q. by Leonard Sands
A. by Tom Haas
Q. What was the bargain that was ultimately struck with the two of them?
A. Once it had been understood that he might be able to supply these things, the understanding I had with Ruddy and Billy was that nothing that Jerry Harvey said to them, or any agent on the Government would ever at any time be used against Jerry Harvey.
Q. And what does that mean, “would ever be used against Jerry Harvey?
A. That he wouldn’t be prosecuted on the basis of what they found out from him.
Q. What instructions or advice did you give Jerry Harvey prior to his attending this meeting at the Sheraton?
A. Well, I told him just what I just said, and I remember that Jerry was very skeptical about that. He didn’t seem to trust anybody, and maybe he didn’t trust me either. Really, he didn’t know me; anything about me. I was a small town lawyer in a small town to him, and I don’t recall who had referred him to me. I usually try to find that out, particularly in drug cases, because I don’t want to get in a situation where I am getting paid by somebody else.
I know that he was skeptical. I know he didn’t trust anybody, and I had to literally force him to comply. I said, “I know these people, U.S. Attorney, and Assistant U.S. Attorney.” I said, “I would stake my life on their honor and veracity."
* * * * $ *
Mr. Sands asked Mr. Kimbrough:
Q. In return for Harvey’s furnishing information, what was he to receive?
A. I was to dismiss the indictment against him.
Q. Do you know whether or not any—
A. And I would not prosecute him for anything he said; and I would not use anything he said as a means of going beyond this agreement to try to stir up trouble for Harvey.
Q. At that time as United States Attorney, you were speaking for yourself, and Southern District of Florida?
A. I can’t say that. It was certainly my understanding that somebody had touched base with South Florida who wanted the information, and I assumed, and I continued to assume that nobody would have—
I certainly would not have asked Mr. Harvey to make a total disclosure had I thought that in doing so, I, you know, turned him loose to prosecution in some other district. I have no personal knowledge of that. That is all I am saying. That is not the way we operated, I assure you. We tried to treat everybody as human beings, although we tried to put some of them in the penitentiary.
* * # * * *
THE COURT: I need to interrupt you, Mr. Sands. Mr. Kimbrough, you made the statement that you would not have prosecuted him for anything he told you about.
Now, there are all different kinds of immunities, and we have been discussing that. We have been discussing transactional immunity versus use immunity.
If in telling you about all drug-related murders about which he had knowledge, Mr. Harvey told you that he killed some*1456body in Mobile, Alabama, pursuant to this agreement, and this letter, and your understanding of this, could you prosecute him for that murder?
THE WITNESS: I don’t know. I probably wouldn’t have.
THE COURT: Could you use his statement or facts that he gave you in the statement in building of the murder case?
THE WITNESS: No, because it would be derived from the statement he gave.
Q. by Leonard Sands
A. by Jerry Lee Harvey
Q. As a result of those conversations, was it your understanding you had an agreement with the U.S. Attorney’s Office in the Southern District of Alabama?
A. I knew I did. Mr. Kimbrough, and Mr. Favre told me, and Tom Haas told me.
Q. What did they tell you your deal was? What were you supposed to do?
A. I was supposed to tell them everything I knew about drug trafficking, people involved, how it took place, what happened to the funds, how you would register airplanes fictitiously. Anything I knew from 1975, and everything I had done from ’75 up to the present time.
Q. And what was the Government’s obligation to you in return for your cooperation?
A. They agreed nothing I ever give them would be used against me, nor would any U.S. Attorney’s office seek to prosecute me for anything; that I was just getting a clean walk, and I should stay on the Government’s side and help them.
# >h # # * #
The best that can be said as a summary of the evidence or statement made by Harvey to the Drug Enforcement Agents at that meeting is that Harvey told them all about his drug dealings in which he had been involved prior to his arrest in June of 1980, and including the arrest of 1980. This Court specifically finds from the facts adduced at the hearing that the defendant Harvey also divulged to the Drug Enforcement Administration his financial dealings with respect to his illegal drug deals.
. Immunity is only available when the testimony is necessary to the public interest and the individual has refused or is likely to refuse to testify on the basis of the privilege. 18 U.S.C. § 6003.
. In 1965, the state Attorney General agreed not to prosecute Rowe in return for his testimony at the grand jury and at trial. After new information arose that Rowe might have lied about whether he actually fired any of the fatal shots, the state attempted to prosecute him for murder. Rowe brought suit under 42 U.S.C. § 1983 to enjoin the state prosecution. 676 F.2d at 525-26.
. I emphasize this point because the majority suggests, supra at 1442-1443, that the only problem is that there is no record of the information provided by Harvey. While that omission is important, it is equally problematic (and ultimately decisive in my mind) that there is no record of the terms of the agreement.
. This is despite the fact that a letter from Mr. Sullivan was introduced in which he asked a state prosecutor to consider the fact that Harvey had cooperated with both the U.S. Attorney and the Drug Enforcement Agency. Additionally, Mr. Sullivan was unable to recall having used Harvey as a witness in a case in which he was the trial prosecutor some three to five years before the agreement.
.I emphasize the narrowness of such a holding. The terms of the agreement, if preserved, might have contradicted Harvey’s interpretation. Even if the agreement was ambiguous, a transcript or even notes of the negotiations might have shown that Harvey’s position is unreasonable.