                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                  No. 07-30182
                Plaintiff-Appellee,           D.C. No.
               v.                         CR-04-00020-6-
DWAYNE EDWARD STRAUB,                           OMP
             Defendant-Appellant.
                                            OPINION

       Appeal from the United States District Court
                for the District of Oregon
        Owen M. Panner, District Judge, Presiding

                  Argued and Submitted
            June 3, 2008—Pasadena, California

                   Filed August 15, 2008

   Before: Dorothy W. Nelson, Andrew J. Kleinfeld, and
              Jay S. Bybee, Circuit Judges.

                 Opinion by Judge Bybee




                           10679
10682              UNITED STATES v. STRAUB


                         COUNSEL

Jeff S. Pitzer, Portland, Oregon, for the appellant.

Kelly A. Zusman, Assistant United States Attorney, United
States Attorney for the District of Oregon, Portland, Oregon,
for the appellee.
                   UNITED STATES v. STRAUB                10683
                          OPINION

BYBEE, Circuit Judge:

   Dwayne Edward Straub challenges his conviction and sen-
tence for narcotics crimes and the attempted robbery and
shooting of Robert Garrett in Portland, Oregon. Straub claims
that the district court’s refusal to compel the prosecution to
grant use immunity to defense witness Mike Baumann vio-
lated his due process rights under the Fifth Amendment. This
case requires us to clarify the standard by which we determine
when a district court must compel the prosecution to grant use
immunity, as most recently stated in Williams v. Woodford,
384 F.3d 567 (9th Cir. 2004). We must address the question
left open by Williams, whether a defendant requesting com-
pelled use immunity on the ground that his witness has rele-
vant testimony that directly contradicts that of an immunized
prosecution witness must prove that the prosecution’s purpose
in denying use immunity to the defense witness was to distort
the fact-finding process, or merely that the prosecution’s
selective denial of use immunity had the effect of distorting
the fact-finding process. See id. at 600-01.

   We have jurisdiction under 28 U.S.C. § 1291, and for the
reasons set forth below, we reverse the district court’s refusal
to compel use immunity and remand for further proceedings.

                               I

                               A

   Straub was arrested on February 6, 2003, following the
execution of a search warrant at his residence in Oregon City,
Oregon. Police found marijuana plants and packaged mari-
juana at Straub’s home. Further investigation uncovered evi-
dence that Straub was involved in a wide-ranging and long-
standing conspiracy to manufacture and distribute metham-
phetamine. As charged in the indictment, Straub was involved
10684                  UNITED STATES v. STRAUB
in the sale and distribution of both marijuana and metham-
phetamine for a continuous period between 1998 and Septem-
ber 2004. Straub was part of a gang known as “The White
Neck Crew” or just “The Crew.” Straub and his associates
were in the business of unlawfully entering the residences of
other drug dealers in order to steal cash and drugs for later
distribution. In the many robberies they committed over a
five-year period, Straub and others wore body armor and dis-
played firearms. The indictment alleged, inter alia, that on
February 8, 2003, Straub and another person carried and used
a firearm in connection with an attempt to rob Robert Garrett
and take more than 100 marijuana plants. Straub allegedly
discharged a firearm in connection with this robbery.

   On November 23, 2004, Straub was charged in a Second
Superseding Indictment with conspiracy, possession with
intent to distribute, and manufacture of methamphetamine and
marijuana.1 Of particular relevance to this appeal, Counts 3
and 4 of the indictment related to the carrying, using, and dis-
charging of a firearm in connection with the attempted rob-
bery of Robert Garrett in his residence on February 8, 2003.
At trial, the prosecution relied heavily on the testimony of
David Adams. Adams was an associate of Straub’s who, at
6′ 5″ and 365 pounds, was known as “Big Mix.” According
to the prosecution’s own stipulation, Adams admitted to par-
ticipating in: (1) the attempted robbery of the home of Robert
   1
     Straub was charged as follows: Count 1, conspiracy to manufacture
and distribute marijuana and methamphetamine, 21 U.S.C. §§ 841(a)(1),
21 U.S.C. § 846(b)(1)(A)(iii), 21 U.S.C. 846(b)(1)(B)(ii); Count 2, manu-
facturing marijuana, 21 U.S.C. § 841(a)(1); Count 3, carrying, using and
discharging a firearm in relation to a drug trafficking crime causing physi-
cal injury to another person, 18 U.S.C. § 924(c)(1)(A)(iii); Count 4,
attempted possession with intent to distribute more than 100 marijuana
plants, 21 U.S.C. § 841(a)(1), 841(b)(1)(B)(vii), 846; Count 5, possession
with intent to distribute more than 350 grams of a mixture containing
methamphetamine, 21 U.S.C. § 841(a)(1), 841(b)(1)(B)(viii); and Count 6
possession with intent to distribute more than 50 grams of “actual”
methamphetamine, 21 U.S.C. § 841(a)(1), 841(b)(1)(B)(viii).
                      UNITED STATES v. STRAUB                      10685
Garrett, during which Garrett was shot in the chest; (2) an
attempt to steal 50 or 60 pounds of marijuana from the home
of Jacob Adams, during which a gun was discharged; and (3)
a series of successful robberies of large quantities of cash,
methamphetamines, and marijuana from homes of local drug
dealers. In exchange for his testimony against Straub, the
prosecution granted Adams use immunity2 for these crimes.3
Adams testified that he participated with Straub in the
attempted robbery of Garrett, and that Straub was the person
who shot Garrett. Adams was the only witness for the prose-
cution who could place Straub at the scene, and the only wit-
ness who could put the gun in Straub’s hand.

   In a colloquy held outside of the presence of the jury,
Straub’s attorney explained to the district judge that he
wanted to impeach Adams by introducing a prior inconsistent
statement, but that the defense witness who could testify as to
the inconsistent statement wanted to assert his Fifth Amend-
ment privilege against self-incrimination. To demonstrate,
Straub’s attorney asked Adams the question he hoped to ask
on the stand: “Mr. Adams, did you have a conversation with
Mike Bauman[n] at a bar in the winter of 2003 in which you
admitted to him that you had just shot a man?” Adams
responded, “No, I didn’t.” Straub’s attorney then stated that
Adams’ response was the statement he planned to impeach
through the testimony of Mike Baumann. The following col-
loquy ensued:
  2
     The government’s power to grant a witness use immunity is conferred
by 18 U.S.C. §§ 6002 and 6003. “Use immunity means that, while the
government may prosecute the witness for an offense related to the subject
matter of the witness’s testimony, the testimony itself and any ‘fruits’
thereof may not be used against the witness in any criminal case except
a prosecution for perjury arising out of the testimony.” United States v.
Lord, 711 F.2d 887, 890 (9th Cir. 1983).
   3
     We discuss the details of the immunity agreement and other incentives
to testify provided by the prosecution in greater detail below.
10686              UNITED STATES v. STRAUB
    [Defense]: I would call Mr. Bauman[n] . . . and it is
    my expectation he would testify that he saw Mr.
    Adams at one of the night clubs . . . and Mr. Adams
    was glum and sullen, and Mr. Bauman[n] asked him
    what’s the matter, and Mr. Adams said, “I just shot
    a man.”

    The Court: Well, I don’t know that that is relevant
    at this point. I mean, he could have shot somebody
    else.

    [Defense]: I would establish the timeframe, Your
    Honor, by the winter of 2003, which is consistent
    with the testimony we’ve been hearing about the
    shooting of Robert Garrett on February 8, 2003.

    The Court: I’m not suggesting that he shot anybody,
    but clearly it’s possible that he could have shot sev-
    eral people about that time period. This is a wild
    story we’re hearing all through the whole case, and
    I can’t conclude from that that he’s talking about this
    case.

    [Defense]: Well, the jurors could draw that infer-
    ence, though, Your Honor, and I think it’s a fair
    inference, and in defending my client I think I have
    the right to present that evidence.

    ***

    [Prosecution]: I believe Mr. Bauman[n] is a fellow
    gang member of the defendant Straub and was iden-
    tified and with him as a gang member in a gang
    investigation in ‘92. The Court knows that gang
    members will take the stand and lie for one another
    and that that is a proper subject of testimony in the
    case. And if Mr. Bauman[n] would come to testify,
    and he certainly may, I intend to examine him:
               UNITED STATES v. STRAUB               10687
Aren’t you a member of the gang with which the
defendant belongs. And aren’t you here lying for
him as a gang member and dealing with it at that
time. I think that’s appropriate.

[Defense]: And, Your Honor, I’m not sure, I’d let
[Mr. Baumann’s lawyer] address this. I’m not sure
that that would raise the Fifth Amendment concerns
if that is as far as the cross-examination went. So—

***

[Mr. Bauman’s Attorney]: My client does wish to
assert a Fifth Amendment privilege. In this case the
Government has alleged a far-reaching conspiracy
and—

The Court: You don’t have to go any further. Based
on [the prosecutor’s] statement about what he
intends to cross-examine about, it’s clear that your
client could be subjected to all kinds of criminal pro-
ceedings including perjury if he doesn’t testify accu-
rately.

So, I — I’m — I guess the ruling properly is that he
can come and testify, but if he does and takes the
Fifth Amendment, I will allow him to remain silent.
I don’t think— [Defense counsel] hasn’t asked me
and I doubt that I would be justified in granting him
any kind of immunity to testify.

[Defense]: That is my last resort, Your Honor, if you
would grant immunity under 18 U.S.C. 6001, the
Government has that opportunity and it’s just inher-
ently unfair for the defendant to have no access to
the same power.

The Court: Under certain circumstances I could
grant immunity, but I don’t think that I should based
10688              UNITED STATES v. STRAUB
    on what you’ve said in your offer of proof. I don’t
    — I don’t think that’s appropriate. So that’s my rul-
    ing. It’s on the record. You can decide whether
    you’re going to call him or not.

    ***

    [Defense]: I don’t intend to call the witness who is
    going to take the Fifth Amendment on the stand in
    front of the jury, Your Honor. And I don’t mean to
    waive my claim to present his evidence, but I do
    think it would be prejudicial to put on a witness and
    take the Fifth.

   Following a five-day trial, Straub was convicted on Counts
1, 3, 4, 5, and 6. On January 23, 2006, the district court sen-
tenced Straub to 152 months on the drug charges (Counts 1,
4, 5, and 6) and an additional statutorily mandated consecu-
tive term of 120 months on the firearms charge (Count 3),
pursuant to 18 U.S.C. § 924(c)(1).

                              B

   Straub timely appealed to this court for the first time on
February 21, 2006. In that appeal, Straub challenged: (1) the
district court’s denial of a motion to sever Counts 3 and 4 of
the indictment from the rest of the trial; and (2) the district
court’s denial of a request to compel the prosecution to grant
use immunity to defense witness Baumann. In an unpublished
memorandum, we held that the district court did not abuse its
discretion in denying the motion to sever. See United States
v. Straub, 224 Fed. App’x 633, 2007 WL 731348 (9th Cir.
March 12, 2007). Considering the district court’s refusal to
compel use immunity, we remanded for an evidentiary hear-
ing because we were unable to determine from the record
whether or not compelled use immunity was constitutionally
required. As we characterized Straub’s position, “[Straub]
does not allege prosecutorial misconduct, but he does main-
                    UNITED STATES v. STRAUB                10689
tain that immunity was warranted because the government
gave immunity or special considerations to many of its wit-
nesses, while refusing immunity for Bauman[n].” Id. at 635.
We stated that on remand, Straub would need to show, inter
alia, that “the government granted immunity to certain wit-
nesses while denying immunity to a witness who would have
‘directly contradicted’ testimony from the immunized govern-
ment witness.” Id. (citing Williams, 384 F.3d at 600). We sug-
gested that the district court gather “[i]nformation on why
Bauman[n] required immunity, greater detail about his pro-
posed testimony and the immunity agreements the govern-
ment gave to its other witnesses.” Id.

                                1

   On April 24, 2007, on remand from this court, the district
court held an evidentiary hearing. The court meticulously fol-
lowed our instructions and gathered the information suggested
by our order. First, the district court cleared the courtroom of
everyone except Baumann and his counsel and took in cam-
era testimony as to why Baumann required immunity. This
portion of the record remains under seal. Although Bau-
mann’s counsel provided more detail in the sealed portion of
the record, his statements only elaborated on the arguments
made in the presence of all parties’ counsel when this issue
was first discussed at Straub’s trial in 2006. In short, the pros-
ecution had stated that if Baumann took the stand, it intended
to attempt to impeach him by soliciting testimony about Bau-
mann’s association with Straub and his membership in the
gang. Given the wide-ranging nature of the conspiracy as
alleged in the prosecution’s indictment, Baumann considered
it necessary to invoke the Fifth Amendment to prevent his tes-
timony to his gang membership being used against him in a
subsequent prosecution for acts of conspiracy related to those
for which Straub was on trial.

  The district court also asked the prosecution what else it
knew about Baumann that would have caused it to prosecute
10690              UNITED STATES v. STRAUB
him. The prosecutor stated that Baumann was found with
Straub on one occasion committing a criminal offense, and
that another witness was willing to testify that Baumann had
loaned Straub money. However, the prosecutor insisted:

    Baumann was not in any way a target of the criminal
    prosecution . . . . Baumann was nowhere on the radar
    screen. He was nowhere of any concern to the Gov-
    ernment as a potential defendant. . . . Baumann was
    not a target. We weren’t after Baumann. We had no
    interest in Baumann as a criminal defendant, and we
    had no evidence that Baumann was involved in this
    conspiracy at all. None whatsoever.

The district responded, “Why didn’t you immunize him?” To
which the prosecutor responded, “I wasn’t asked.”

   Next, the district court gathered evidence on the grants of
immunity given by the prosecution to Adams and other gov-
ernment witnesses. This evidence was provided by an
Amended Joint Stipulation of Facts entered into by the par-
ties. According to the Stipulation, despite Adams’ having
admitted to attempted armed robbery and numerous other
thefts of cash and drugs, Adams was provided use immunity
“except with respect to violent crimes” in exchange for his
testimony. Although the formal agreement did not grant
immunity for violent crimes, it appears Adams was given
informal immunity, as he was never prosecuted for any of his
violent crimes. Adams was charged with a single count of
intimidation of a federal witness, in violation of 18 U.S.C.
§ 1512. For this one crime, Adams pleaded guilty, and in the
plea agreement, the government agreed “not to file or seek
any new or additional charges against [Adams] . . . arising out
of the investigation of this case.” At sentencing for this con-
viction, the judge noted that Adams’ sentence represented a
downward departure of “three or four or five years because of
[his] cooperation” with the government. According to the
Stipulation, Adams was released from prison on October 26,
                  UNITED STATES v. STRAUB              10691
2006, while Straub’s projected release date, stemming from
the convictions which Adams’ testimony helped secure, was
February 26, 2024.

   The Joint Stipulation also provided evidence as to the
incentives—use immunity, informal immunity, sentence
reductions, and even cash—offered to the prosecution’s other
witnesses for their testimony against Straub. The Stipulation
is long, and we need not recount every detail. In summary, of
the thirteen witnesses the government and Straub called or
intended to call, eleven of the twelve government witnesses
received some kind of immunity or other benefits. Most of
these witnesses admitted to significant federal crimes. For
example, Dustin Alsup testified that he: (1) partnered with
another gang member in drug trafficking; (2) was arrested
after a Tupperware container full of methamphetamines was
found in his freezer; (3) grew a “large amount” of marijuana
plants; (4) manufactured methamphetamines in a house in the
area; (5) continued to make and distribute methamphetamines
in another location; (6) sold a minimum of 40 pounds of
methamphetamines for at least $200,000 and a minimum of
40 pounds of marijuana for at least $100,000; (7) bought
drugs from Straub; and (8) manufactured “pounds and
pounds” of methamphetamines over the years. Shortly after
he was arrested, Alsup entered into a proffer agreement with
the government which provided him with use immunity. In
addition, Alsup agreed to plead guilty for possession with
intent to distribute at least 15 grams of methamphetamines,
which carried a 10-year minimum sentence. Despite his testi-
mony that he had manufactured and sold great quantities of
drugs, and despite his pleading to a crime with a 10-year
minimum sentence, Alsup was eventually sentenced to only
30 months in prison, all in exchange for his cooperation with
the government.

  As another example, Jacob McCord testified that he (1) was
a methamphetamine cook for several years; (2) assisted
Straub in growing marijuana at Straub’s house; (3) stole 40
10692              UNITED STATES v. STRAUB
marijuana plants from Straub; (4) used drugs; (5) sold 50
pounds of methamphetamine to Straub for $300,000; (6) pur-
chased chemicals for use in manufacturing methamphet-
amines; (7) had 120 grams of methamphetamine seized from
his house by police; and (8) obtained chemicals for further
methamphetamine manufacturing while on pretrial release.
McCord knew he faced a Guidelines-recommended sentence
of 135 to 168 months for the 120 grams of methamphetamines
alone, and that he faced a minimum of 10 years under the
drug statute. In exchange for his testimony against Straub,
McCord was permitted to plead guilty to possession with
intent to distribute, and, following his testimony against
Straub, his sentence was reduced to 63 months in prison.
McCord was also never charged with possessing a loaded .38
caliber pistol found on the floor of one of his residences. As
a final example, Jason Shaw testified to being a methemphet-
amine dealer for a few months, a “big” drug dealer for a cou-
ple of years, growing several marijuana plants, and using
drugs himself. Shaw was paid a total of $8,300 for providing
assistance to state and federal governments in drug investiga-
tions. He was also given informal immunity and “expects not
to be prosecuted for any crime.” In addition to these three and
David Adams, the government granted immunity or some
other kind of benefit to Grant McFarland, Jeff Center, Anita
Wealand, Lisa Clark, Cory Don Smith, Joseph Mockley, and
Jacob Adams. The government did not grant immunity to one
of its witnesses, Misty Dawn Day, who testified that she is a
drug user.

  The one defense witness listed in the Stipulation, Mike
Baumann, was denied use immunity.

  Finally, the district court moved on to the issue of whether
Baumann’s testimony would have directly contradicted
Adams’ testimony. Adams was prepared to testify that he did
not walk into a bar in the winter of 2003 and tell someone that
he shot a man. Baumann was prepared to testify that on Feb-
ruary 8, 2003, Adams walked into a club, acting “very glum
                        UNITED STATES v. STRAUB                       10693
and quiet and morose,” and told Baumann, “I just shot a man.”4
Straub’s counsel5 explained the importance of this contradic-
tion:

      If that evidence had been heard, if that testimony had
      been heard by the jury, [the defense counsel] could
      have argued that based on that[,] Mr. Adams was
      himself perhaps the shooter of Robert Garrett. That
      perhaps his credibility was so suspect, if he’s willing
      to lie about the key element of his testimony, the
      shooter who shot Robert Garrett, if he’s lying about
      that, the jury could have discredited his testimony in
      its entirety.

      . . . [T]here were already a host of credibility prob-
      lems with Mr. Adams, as the Government admits.
      He admitted to lying to the police, he admitted to
      lying to the Government when it helps him, espe-
      cially when he could help himself. He admitted to
      threatening to beat up his own grandmother. He
      admitted to numerous drug and violent crimes. His
      credibility was already hanging in the balance,
      Judge.

      And if Michael Baumann could testify, it could have
      been the tipping point that the jury would have used
      to discredit Adams’ testimony in its entirety. And if
      they had done that, they likely would have
      acquit[t]ed on Counts 3 and 4[, ] having to do with
      the Robert Garrett shooting. And that resulted in Mr.
  4
     Baumann himself never testified, either at trial or in a colloquy outside
of the presence of the jury. At different hearings, the parties’ attorneys
described what Adams told Baumann variously as “I just shot a man,” “I
just shot a guy,” and “I’ve shot somebody.” These discrepancies are irrele-
vant to this appeal.
   5
     Straub was represented by new counsel beginning with the first appeal
to our court.
10694                UNITED STATES v. STRAUB
      Straub getting 10 extra years in prison. Instead of 13
      years he gets 23 years. So he has to sit in prison for
      ten extra years wondering every day what might
      have happened if Michael Baumann had testified.

   The prosecution made several arguments in rebuttal. It
argued that Adams was not the star witness Straub made him
out to be. Because the trial judge gave a Pinkerton instruction,6
the jury did not need to find that Straub held the gun in order
to hold him liable. This, the prosecution argued, downplayed
the importance of Adams being the only witness to place the
gun in Straub’s hand—the jury could have convicted whether
it was Straub or Adams who pulled the trigger. The prosecu-
tion also argued that the testimony of Misty Dawn Day sup-
ported its case on Counts 3 and 4. Day testified that, while
high on marijuana, she overheard Straub and Adams planning
the robbery through a closed door. The prosecutor conceded
that the government had given numerous incentives to many
witnesses to testify against Straub, but he represented that
there was no intent to distort the fact-finding process. The
prosecutor also reiterated that he was never formally asked to
give immunity to Baumann.

                                  2

   On May 11, 2007, the district court entered an order again
denying Straub’s request to compel the government to offer
use immunity to Baumann. The court recounted that the pros-
ecution represented that it “had no interest in Baumann as a
criminal defendant . . . . None whatsoever.” At the same time,
the court noted, the prosecutor had asserted that “Baumann
was found with this defendant . . . committing a criminal
offense . . . . And Baumann was in fact . . . a gang member,
a friend of the defendant.” The prosecutor had also made clear
that his cross-examination of Baumann would begin by draw-
ing out information about Baumann’s gang membership and
  6
   Pinkerton v. United States, 328 U.S. 640 (1946).
                      UNITED STATES v. STRAUB                      10695
willingness to do anything for Straub. Under these circum-
stances, the district court re-affirmed its prior ruling that Bau-
mann’s assertion of privilege was proper, citing Kastigar v.
United States, 406 U.S. 441, 445 (1972), and United States v.
Hoffman, 341 U.S. 479, 486 (1951).7

   Turning to the issue of whether the prosecution’s conduct
had distorted the fact-finding process, the district court
expressed some hesitation as to the Ninth Circuit law on this
issue. The court stated that it could not be sure from our pre-
cedents in Williams, Young, Baker, and Westerdahl whether,
in order to compel use immunity, Straub had to prove that the
denial of use immunity to Baumann implicated prosecutorial
misconduct. See Williams, 384 F.3d at 600; United States v.
Young, 86 F.3d 944, 949 (9th Cir. 1996); United States v.
Baker, 10 F.3d 1374, 1415 (9th Cir. 1993), overruled on other
grounds, United States v. Nordby, 225 F.3d 1053 (9th Cir.
2000); United States v. Westerdahl, 945 F.2d 1083, 1087 (9th
Cir. 1991). The district court was unclear as to whether Straub
must prove that the prosecution acted with the purpose of dis-
torting the fact-finding process, or merely that the prosecu-
tion’s conduct had the effect of distorting the fact-finding
process. Therefore, the court made alternative rulings under
each theory.

   The court ruled that if prosecutorial conduct is a required
element—that the prosecution acted with the purpose of dis-
torting the fact-finding process—then Straub’s claim failed.
As we had noted in our memorandum, Straub did not allege
prosecutorial misconduct. See Straub, 224 Fed. App’x at 635.
Thus, he was not entitled to compel use immunity under a
“purpose” theory.
  7
    We recount the district court’s ruling on whether Baumann properly
invoked the Fifth Amendment only to enrich the record. The propriety of
the witness’s invocation of the Fifth Amendment is not a prong of the test
for compelled use immunity. See Williams, 384 F.3d at 600. Our opinion
should not be construed as adding any such prong.
10696              UNITED STATES v. STRAUB
   The court then considered Straub’s claim under the theory
that a showing of the mere effect of distorting the fact-finding
process was sufficient. The court found that the testimony of
David Adams was “crucial” to the prosecution’s case on
Counts 3 and 4. Adams was the only witness who testified
that Straub was armed on the night of the robbery. Adams
also testified that, although he did not see Straub shoot Gar-
rett, he heard the gunshot, and that he saw Straub fire other
shots that night and during a previous robbery. The district
court acknowledged the prosecution’s argument that because
of the Pinkerton instruction, the jury could have theoretically
convicted Straub even if it did not believe he was the shooter.
“Nevertheless,” the court ruled, “the testimony of Adams was
important to the prosecution’s case. If a jury believed that
Adams lied about this, and was shifting the blame to Straub
for his own actions, it would seriously weaken the govern-
ment’s case on counts three and four . . . . The defense could
have argued that Adams, not Straub, orchestrated the Garrett
robbery and shooting, without Straub’s involvement or
knowledge.” The district court also considered the prosecu-
tion’s arguments about Misty Dawn Day, but found that
“[D]ay’s testimony, by itself, would not be enough to sustain
a conviction on counts three and four.”

   The district court then ruled that Straub’s claim failed
because the testimony of Mike Baumann did not “directly
contradict” that of Adams. See Williams, 384 F.3d at 600
(holding that the testimony must have “directly contradicted”
testimony from the immunized government witness). The
court noted that Adams was prepared to deny that on the night
in question he told Baumann, “I just shot a guy,” and that
Baumann was prepared to testify that Adams told him, “I just
shot a guy.” The court ruled, however, that even if Adams did
say, “I just shot a guy,” this did not prove he actually shot
someone. “Adams might have been joking, or trying to appear
tough,” or indicating he was merely present when Garrett was
shot. Furthermore, the court ruled, “even accepting the Bau-
mann proffer literally, it does not prove Adams was referring
                   UNITED STATES v. STRAUB              10697
to Garrett.” The court concluded that Baumann’s testimony
“would have given the defense some additional ammunition
in attacking the credibility of Adams, but would not ‘directly
contradict’ the most important testimony by Adams, nor
clearly exonerate Straub on these two counts.” The court
declined to compel use immunity. Straub appealed for a sec-
ond time.

                              II

   The question of whether a district court erred by refusing
to compel use immunity is a mixed question of law and fact
that we review de novo. United States v. Alvarez, 358 F.3d
1194, 1216 (9th Cir. 2004). Factual findings underlying the
district court’s ruling are reviewed for clear error. Id.

  [1] There are important separation of powers concerns pres-
ent in a request to compel immunity:

    It has long been recognized that the Executive
    Branch of government has exclusive authority and
    absolute discretion to decide whether to prosecute a
    case . . . . To interpret the Fifth and Sixth Amend-
    ments as conferring on the defendant the power to
    demand immunity for co-defendants, potential co-
    defendants, or others whom the government might in
    its discretion wish to prosecute would unacceptably
    alter the historic role of the Executive Branch in
    criminal prosecutions. Of course, whatever power
    the government possesses may not be exercised in a
    manner which denies the defendant the due process
    guaranteed by the Fifth Amendment.

United States v. Alessio, 528 F.2d 1079, 1081-82 (9th Cir.
1976) (internal quotation marks and citations omitted). Our
test for when due process requires that the district court
impede on the discretion of the executive branch and compel
10698              UNITED STATES v. STRAUB
use immunity has evolved over time. In Williams, we stated
the test as follows:

    [T]he prosecution’s refusal to grant use immunity to
    a defense witness denies the defendant a fair trial
    only when (1) the witness’s testimony would have
    been relevant, and (2) the prosecution refused to
    grant the witness use immunity with the deliberate
    intention of distorting the fact-finding process. . . .
    To demonstrate the prosecutorial misconduct of the
    second prong, [the defendant] must show that the
    prosecution intentionally caused a defense witness to
    invoke the Fifth Amendment right against self-
    incrimination, or that the prosecution granted immu-
    nity to a government witness in order to obtain that
    witness’s testimony, but denied immunity to a
    defense witness whose testimony would have
    directly contradicted that of the government witness.

384 F.3d at 600 (citations omitted and emphases added).

   As the district court observed, the facts of this case have
isolated an ambiguity in our test as stated in Williams. The
second prong of the test is that “the prosecution refused to
grant the witness use immunity with the deliberate intention
of distorting the fact-finding process.” Id. (emphasis added).
Williams stated that prong may be satisfied in one of two
ways. One would expect that both methods are designed to
prove “deliberate intention.” However, the two alternative
methods of showing misconduct differ in that only the first
describes conduct with a particular intent: “the prosecution
intentionally caused a defense witness to invoke” his Fifth
Amendment rights. Id. The second merely requires showing
that “the prosecution granted immunity to a government wit-
ness in order to obtain that witness’s testimony, but denied
immunity to a defense witness whose testimony would have
directly contradicted that of the government witness.” Id. The
Williams test uses the word “or” between the two methods for
                    UNITED STATES v. STRAUB                10699
proving the second prong of the test, suggesting that the two
methods are disjunctive; only one need be proven, not both.
Both parties agreed to this at oral argument. Thus, our test as
it has been refined over time suggests that one may prove that
the prosecution acted with a certain purpose merely by dem-
onstrating that the prosecution committed a set of acts (the
selective denial of use immunity described) that had the effect
of distorting the fact-finding process. Straub has conceded
that the prosecution did not act with the purpose of distorting
the fact-finding process. He argues that he is entitled to a
grant of use immunity because the government’s conduct oth-
erwise met the Williams test and had the effect of distorting
the fact-finding process.

   In order to determine whether Straub is correct, we first
work through the first prong and first alternative method for
proving the second prong as they apply to Straub. We then
turn to the cases leading to Williams for guidance in interpret-
ing Williams. Because, as discussed below, we find that our
precedents lead to the conclusion that a showing of effects is
sufficient, we then apply this method of proving the second
prong of the Williams test to Straub’s claim.

                                A

    The first prong under the Williams test is that “the witness’s
testimony would have been relevant.” 384 F.3d at 600. We
have described the relevance requirement for purposes of the
Williams test as “minimal.” Id. The defendant “need not show
that the testimony sought was either clearly exculpatory or
essential to the defense.” Westerdahl, 945 F.2d at 1086 (inter-
nal quotation marks omitted). In our previous memorandum
disposition, we found that Baumann’s testimony was relevant
because it raised credibility questions about a key prosecution
witness. See 224 Fed. App’x at 635. As the district court put
it, “Baumann’s testimony would have given the defense some
additional ammunition in attacking the credibility of Adams.”
If the jury credited Baumann, it could have found that Adams
10700                 UNITED STATES v. STRAUB
was a perjurer and might even be lying to shift the blame for
his own conduct on to Straub. Straub satisfies the first prong.

   [2] The second prong under the Williams test is that “the
prosecution refused to grant the witness use immunity with
the deliberate intention of distorting the fact-finding process.”
Williams, 384 F.3d at 600. As the first of two alternative
methods, the defendant may satisfy this prong by showing
“that the prosecution intentionally caused a defense witness to
invoke the Fifth Amendment right against self incrimination.”
Id. This method includes the word “intentionally.” In one
sense, any time the prosecution causes a witness to invoke his
Fifth Amendment right, this could be described as “intention-
al.” A decision to cross-examine a defense witness is a prod-
uct of strategic analysis by the prosecution. The inclusion,
then, of the word “intentional” in Williams suggests that the
defendant seeking to compel immunity must demonstrate
something more than the prosecution’s mere “intention” to
cross-examine the witness.8 Our cases have insisted that the
government’s actions need to amount to something akin to
prosecutorial misconduct. In Williams, we stated that resolu-
tion of this claim “turns on whether the prosecution took affir-
mative steps to prevent Williams’s witnesses from testifying.”
384 F.3d at 601 (emphasis added). We elaborated:

      Undue prosecutorial interference in a defense wit-
      ness’s decision to testify arises when the prosecution
      intimidates or harasses the witness to discourage the
      witness from testifying, for example, by threatening
      the witness with prosecution for perjury or other
      offenses. . . . The prosecution’s conduct must
  8
   As Straub conceded at oral argument, there may be occasions where
the defense witness decides on his own to invoke the Fifth Amendment,
even in the absence of an indication from the prosecution that it intends
to cross-examine the witness. Such a scenario would not satisfy the
requirement that “the prosecution intentionally caused a defense witness
to” take the Fifth.
                    UNITED STATES v. STRAUB                10701
    amount to a substantial interference with the defense
    witness’s free and unhampered determination to tes-
    tify before the conduct violates the defendant’s right
    to due process.

Id. at 601-02; see also United States v. Lord, 711 F.2d 887,
891 (9th Cir. 1983) (holding that the record supported finding
that “prosecutorial misconduct” caused the defense witness to
invoke his Fifth Amendment privilege because the prosecutor
told the witness that “whether he would be prosecuted
depended on his testimony”); United States v. Paris, 827 F.2d
395, 401 (9th Cir. 1987); United States v. Touw, 769 F.2d
571, 573 (9th Cir. 1985). As Straub has not alleged prosecu-
torial misconduct, he cannot prevail under this theory.

                               B

   [3] The alternative way that a defendant may satisfy the
second prong of the Williams test is by showing that “that the
prosecution granted immunity to a government witness in
order to obtain that witness’s testimony, but denied immunity
to a defense witness whose testimony would have directly
contradicted that of the government witness.” 384 F.3d at 600.
As discussed above, ambiguity arises because demonstrating
that the conduct described, which we shall refer to as the “se-
lective denial of immunity,” had the effect of distorting the
fact-finding process does not necessarily demonstrate that the
prosecution had the “deliberate intention of distorting the fact-
finding process.” Id. A careful review of our cases leads us to
the conclusion that, notwithstanding this ambiguity in phras-
ing, a showing that the selective denial of immunity had the
effect of distorting the fact-finding process is sufficient.

                               1

   Few of our cases considering compelled use immunity have
had to confront the purpose/effects question, because there,
since the defendant’s witnesses frequently offered evidence
10702              UNITED STATES v. STRAUB
that was irrelevant, we had no need to consider the purpose
or effect of the government’s denial of immunity. See, e.g.,
United States v. Alvarez, 358 F.3d 1194, 1216 (9th Cir. 2004)
(the testimony sought did not directly contradict statements by
the government’s witnesses); United States v. Brutzman, 731
F.2d 1449, 1452 (9th Cir. 1984) (the testimony was cumula-
tive or “not exculpatory”); Alessio, 528 F.2d at 1082 (“The
testimony sought by appellant was cumulative . . . .”).

   In Lord, our earliest case to develop a test for compelled
use immunity, we adopted the Third Circuit’s rule that “ ‘[t]he
defendant must be prepared to show that the government’s
decisions were made with the deliberate intention of distorting
the judicial fact[-]finding process.’ ” 711 F.2d at 890 (quoting
United States v. Herman, 589 F.2d 1191, 1204 (3d Cir.
1978)). Lord also adopted the Third Circuit’s subsequent
developments of this rule, in Virgin Islands v. Smith, 615 F.2d
964 (3d Cir. 1980). As Lord describes Smith, the refined test
was:

    whether the federal prosecutor, in refusing to consent
    to extending immunity to the defense witness, acted
    with a deliberate intention of distorting the fact-
    finding process. . . . If the district court found that
    prosecutorial misconduct had prevented the defense
    witness from giving relevant testimony, then the
    court was directed to acquit the defendant unless the
    prosecutor granted use immunity to the defense wit-
    ness.

711 F.2d at 891 (citations omitted). Thus, Lord required pro-
secutorial misconduct as an element of the test. However,
Lord did not consider selective denial of immunity that was
admittedly not prosecutorial misconduct but that had the
alleged effect of distorting the fact-finding process. Lord only
considered a claim under the other method of showing pro-
secutorial misconduct—intentionally causing a defendant to
take the Fifth. The dispositive fact was that the defense wit-
                    UNITED STATES v. STRAUB                10703
ness “testified that before trial the prosecutor told him that
whether he would be prosecuted depended on his testimony.”
Id. Lord remanded for “further clarification of the prosecu-
tor’s pre-trial comments” to the defense witness. Id.

   We expanded the test for compelled immunity in Wester-
dahl. We began with the acknowledgment that if the prosecu-
tion intentionally caused the witness to invoke the Fifth
Amendment, the law of our circuit clearly compelled a grant
of use immunity: “In the past, our decisions on prosecutorial
misconduct have focused on whether the government or its
agents took affirmative actions to prevent defense witnesses
from testifying.” 945 F.2d at 1086. We then suggested that a
“selective denial of immunity” test was also viable:
“[M]isconduct is not confined solely to situations in which the
government affirmatively induces a witness not to testify in
favor of a defendant.” Id. at 1087. Although Lord only dealt
with a claim that the prosecution intentionally caused a
defense witness to invoke the Fifth Amendment, we reasoned
that “[f]or the government to grant immunity to a witness in
order to obtain his testimony, while denying immunity to a
defense witness whose testimony would directly contradict
that of the government witness, is the type of fact-finding dis-
tortion we intended to prevent in Lord.” Id. We remanded for
an evidentiary hearing, saying that “where two eyewitnesses
tell conflicting stories, and only the witness testifying for the
government is granted immunity, the defendant would be
denied any semblance of a fair trial” and thus compelled
immunity would be the proper remedy. Id. (internal citation
and quotation marks omitted).

   Our subsequent opinions have continued to state that there
are two methods by which the defendant seeking to compel
immunity may demonstrate a distortion of the fact-finding
process, but none have been presented with the purpose/effect
issue we confront here. In United States v. Baker, for exam-
ple, we summarized the test for compelled immunity,
acknowledging both the Lord test and the Westerdahl test. 10
10704              UNITED STATES v. STRAUB
F.3d at 1414. In that case, the defendant’s claim for com-
pelled immunity was so weak on so many elements that we
had no occasion to consider the purpose/effect question. The
individual that the defense sought to exonerate with testimony
from a witness who was denied use immunity was not even
charged with the murder about which the non-immunized wit-
ness could testify. See id. 1414-15. Moreover, the proffered
testimony was inadmissible hearsay. In United States v.
Young, we found strong evidence that the defendant’s witness
did in fact have relevant testimony that would have
impeached the government’s star witness. See 86 F.3d at 948.
Holding that the defendant likely had a strong claim for com-
pelled immunity under Westerdahl, we remanded for an evi-
dentiary hearing “as to whether the government intentionally
distorted the fact-finding process.” Id. at 949. We had no
occasion to consider whether the mere effect of distorting the
fact-finding process might be sufficient. See also United
States v. Duran, 189 F.3d 1071, 1087 (9th Cir. 1999) (holding
that defendant had not demonstrated either the Lord or
Westerdahl bases for compelling immunity).

                               2

   [4] We conclude that our statement of the test for com-
pelled immunity in Williams, to the extent it appears ambigu-
ous, merely reflects the fact that while we have previously
suggested that an effects test is viable, we have never yet been
presented with such a case. It is equally clear that our juris-
prudence has anticipated endorsing an effects test where the
other elements of the test have been satisfied. The separation
of powers concerns implicated by compelled immunity sug-
gest that we should be hesitant in expanding Williams; never-
theless, the logic of Williams and the cases it drew from
supports the adoption of an effects test. Even where the gov-
ernment has not denied a defense witness immunity for the
very purpose of distorting the fact-finding process, the gov-
ernment may have stacked the deck against the defendant in
a way that has severely distorted the fact-finding process at
                   UNITED STATES v. STRAUB                10705
trial. See Westerdahl, 945 F.2d at 1087 (“Previously, we
noted in dicta that where two eyewitnesses tell conflicting sto-
ries, and only the witness testifying for the government is
granted immunity, the defendant would be denied ‘any sem-
blance of a fair trial.’ ” (quoting Brutzman, 731 F.2d at 1452).
In those cases where the government has liberally used its dis-
cretion to grant immunity to numerous witnesses, and the
defendant’s witness could offer relevant testimony that would
directly contradict that of an immunized government witness,
the trial may become so fundamentally unfair that the defen-
dant’s due process rights are implicated.

   Our approach is consistent with Supreme Court authority
on due process at trial. When dealing with due process rights
“outside the courtroom,” the Court has been hesitant to find
constitutional violations by law enforcement absent some
kind of malicious intent. See, e.g., County of Sacramento v.
Lewis, 523 U.S. 833, 842, 855 (1998) (noting that “we have
always been reluctant to expand the concept of substantive
due process” and holding that a high-speed police car chase
does not violate substantive due process unless the officer
acted with intent to harm (quotation marks and citation omit-
ted)); Daniels v. Williams, 474 U.S. 327, 328, 331-32 (1986)
(holding that a prisoner’s due process rights were not violated
when he slipped on a pillow negligently left on the stairs by
a correctional deputy, because “[h]istorically, [the] guarantee
of due process has been applied to deliberate decisions of
government officials to deprive a person of life, liberty, or
property”); Bingue v. Prunchak, 512 F.3d 1169, 1177 (9th
Cir. 2008) (approving the Eighth Circuit’s observation that
the Court’s reluctance to expand the concept of substantive
due process suggests that the intent to harm standard applies
to both emergency and non-emergency high-speed police car
chases). However, when dealing with due process violations
in the context of the fundamental fairness of the trial, the
Supreme Court has been more concerned with protecting the
integrity of trial and the defendant’s right to mount a defense,
irrespective of any government intent to interfere with these
10706              UNITED STATES v. STRAUB
rights. The Due Process Clause addresses the defendant’s
right to a fair trial, not just whether the government intended
to deny the defendant his rights. See, e.g., Brady v. Maryland,
373 U.S. 83, 87 (1963) (holding that “the suppression by the
prosecution of evidence favorable to an accused upon request
violates due process . . . irrespective of the good faith or bad
faith of the prosecution” (emphasis added)); cf. Estelle v. Wil-
liams, 425 U.S. 501, 503-05 (1976) (holding that compelling
the accused to stand trial in jail garb violates due process
because it inherently impairs the jury’s basic presumption of
the defendant’s innocence). The Court has also been more
willing to find violations of other constitutional rights that
affect the fairness of trial even where there is no intent to
harm the accused’s defense. See, e.g., Doggett v. United
States, 505 U.S. 647, 656-57 (1992) (holding that the govern-
ment may violate the defendant’s Sixth Amendment speedy
trial right even if it had no intent to harm the accused’s
defense). Moreover, the Court has repeatedly held that the
Sixth Amendment may require courts to hold unconstitutional
(as applied) certain evidentiary rules and privileges that pre-
vent a defendant from mounting his defense—regardless of
the purpose of the rule. See Rock v. Arkansas, 483 U.S. 44,
51-53, 62 (1987); Davis v. Alaska, 415 U.S. 308, 320 (1974);
Chambers v. Mississippi, 410 U.S. 284, 294-95 (1973); Wash-
ington v. Texas, 388 U.S. 14, 19 (1967). The right to compel
use immunity because of selective denial of immunity is a
right to due process “inside the courtroom,” where the Consti-
tution focuses our attention on the fundamental fairness of the
trial more than on the intentions—whether good or bad—of
the prosecution.

   Finally our conclusion that an effects test is viable is sup-
ported by considering the remedy the defendant seeks. The
court’s decision to compel use immunity is not a sanction for
prosecutorial misconduct; it is a vindication of the defendant’s
Fifth Amendment due process right to a trial in which the
fact-finding process has not been distorted. See Lord, 711
F.2d at 892 (“[T]he key issue in the analysis of defense use
                    UNITED STATES v. STRAUB                10707
immunity is whether the defendant was denied a fair trial.”).
Because compelling use immunity is not a sanction for pro-
secutorial misconduct, it follows that the defendant need not
prove that the prosecution acted intentionally to distort the
fact-finding process where the other elements of the Williams
test are met. Moreover, the remedy granted is neither an auto-
matic acquittal for the defendant, nor an automatic grant of
use immunity for the defense witness. In the Lord scenario, in
which the prosecution intentionally caused the defense wit-
ness to invoke the Fifth, “[i]f the district court finds such pro-
secutorial misconduct by a preponderance of the evidence, it
should enter a judgment of acquittal for [the defendant] unless
the prosecution invokes 18 U.S.C. §§ 6002-6003 by asking
the district court to extend use immunity to [the defense wit-
ness] at a new trial.” Id. (footnote omitted). Where use immu-
nity is required because of a selective denial of use immunity
that had the effect of distorting the fact-finding process, the
prosecution has a third option as well: it may, at a new trial,
attempt to proceed without the witness whose testimony
would have been contradicted by the defense witness. These
three options give the prosecution several choices and provide
some mitigation for the intrusion on prosecutorial discretion
that compelled use immunity causes.

   A survey of our opinions suggests that in the majority of
cases where a defendant seeks to compel immunity for a wit-
ness, that witness’s testimony will not be “directly contradic-
tory” to that of the prosecution’s witness, or there will have
been no distortion of the fact-finding process, and the district
court may deny immunity on those bases. See Alvarez, 358
F.3d at 1216 (the testimony sought did not directly contradict
statements by the government’s witnesses); Duran, 189 F.3d
at 1087 (neither the Lord test nor the Westerdahl test was
even applicable); Baker, 10 F.3d at 1414-15 (defendant not
even charged with the crime about which defense witness
offered testimony); Brutzman, 731 F.2d at 1452 (evidence
was cumulative or “not exculpatory”); Alessio, 528 F.2d at
1082 (“The testimony sought by appellant was cumulative .
10708               UNITED STATES v. STRAUB
. . .”). As we discuss below, this case appears to be the rare
case in which the testimony was in fact directly contradictory.
Furthermore, the prosecution granted immunity and other
incentives to eleven of Straub’s co-conspirators, while deny-
ing immunity to the one witness who had testimony that, if
believed, would make the government’s key witness both a
perjurer and possibly the actual perpetrator of the crime.
There is an unmistakable air of unfairness to a trial conducted
under these circumstances, one that calls into question the
fundamental fairness of Straub’s trial and the meaningful pro-
tection of his due process rights.

   [5] In conclusion, we find that any ambiguity in Williams
arose because Williams and its predecessors recognized the
possibility of the case we have before us, but had not con-
fronted such a case. We now hold that for a defendant to com-
pel use immunity the defendant must show that: (1) the
defense witness’s testimony was relevant; and (2) either (a)
the prosecution intentionally caused the defense witness to
invoke the Fifth Amendment right against self-incrimination
with the purpose of distorting the fact-finding process; or (b)
the prosecution granted immunity to a government witness in
order to obtain that witness’s testimony, but denied immunity
to a defense witness whose testimony would have directly
contradicted that of the government witness, with the effect of
so distorting the fact-finding process that the defendant was
denied his due process right to a fundamentally fair trial.

                               3

   [6] Having clarified the applicable law, we turn to the dis-
trict court’s ruling that, even under an effects test, Straub was
not entitled to compel use immunity for Baumann. We have
already stated that Baumann’s testimony would have been rel-
evant and that Straub concedes the prosecution did not inten-
tionally cause Baumann to invoke the Fifth Amendment.
Thus, we consider only whether the prosecution granted
immunity to a government witness in order to obtain the wit-
                   UNITED STATES v. STRAUB                10709
ness’s testimony but denied immunity to a defense witness
whose testimony would have directly contradicted that of the
government witness, with the effect of so distorting the fact-
finding process that the defendant was denied his due process
right to a fundamentally fair trial.

   [7] It is undisputed that the prosecution granted immunity
to Adams in order to obtain Adams’ testimony. We must next
determine whether Baumann’s testimony would have “di-
rectly contradicted,” Williams, 384 F.3d at 600, that of
Adams. Straub’s attorney was prepared to ask Adams: “Mr.
Adams, did you have a conversation with Mike Bauman[n] at
a bar in the winter of 2003 in which you admitted to him that
you had just shot a man?” Adams intended to reply: “No, I
didn’t.” Baumann would have testified that, some time during
the winter of 2003, Adams walked into a bar looking “glum
and sullen,” and said, “I just shot a guy.” If Baumann is pre-
pared to testify that Adams stated, “I just shot a guy,” and
Adams is prepared to deny having made the statement, we
have no trouble concluding that Baumann’s testimony would
have “directly contradicted” that of Adams, and accordingly
that Straub has satisfied this element of the test for compelled
immunity.

   The district court gave several reasons why Baumann’s tes-
timony did not “directly contradict” that of Adams. First, the
district court stated that, even if Adams made the statement,
it does not prove that he actually shot someone. He could
have been joking or bragging. The court also reasoned that
even if Adams had meant that he shot “someone,” there was
no proof the statement was an admission of shooting Garret.
The district court erred because Baumann’s statements, if
believed by the jury, could also support a finding that Adams
lied on the stand and possibly that Adams was the shooter.
The Williams test requires only that the testimony “directly
contradict” the government witness’s testimony on a relevant
issue, not that the testimony have compelled the jury to exon-
erate the defendant. Adams told the prosecution that he did
10710              UNITED STATES v. STRAUB
not tell Mike Baumann that he shot someone. Mike Baumann
said Adams did tell him that he shot someone. This is, simply
put, a direct contradiction. Adams may have been joking, or
he may have shot someone other than Garrett, but these are
matters for counsel to probe and the jury to decide. Bau-
mann’s testimony satisfies the test for “directly contradictory”
because the testimony, if believed by the jury, could have sup-
ported a finding that the testimony directly contradicted that
of the government’s witness. The jury might have thought that
it was implausible that Adams was joking or bragging if he
appeared morose, and that it was unlikely that Adams shot
two men during the same time period and more likely that he
shot only one, Garrett.

   The fact that the proffered testimony need only support (as
opposed to compel) a finding by the jury that it was “directly
contradictory” is implied by the rest of the Williams test. The
first prong of the test is that the proffered testimony be rele-
vant. Williams, 384 F.3d at 600. We have cautioned that the
relevance requirement is “minimal.” See id. The defendant
“need not show that the testimony sought was either ‘clearly
exculpatory’ or ‘essential to the defense.’ ” Westerdahl, 945
F.2d at 1086. It would narrow the due process right signifi-
cantly if the test allows a low showing of relevance to pass the
first prong, only to require that the same evidence must com-
pel the jury to find that it is “directly contradictory” for the
second prong. A brick, of course, is not a wall, and it would
contravene the holdings of Williams, Westerdahl, and Lord to
require that a defendant proffer a wall in order to compel use
immunity for his brick.

   [8] Finally, we must consider whether the prosecution’s
refusal to grant use immunity to Baumann had the effect of
so distorting the fact-finding process that the defendant was
denied his due process right to a fundamentally fair trial. The
district court found that Adams’s testimony was “crucial” to
the prosecution’s case. Adams was the only witness who testi-
fied Straub was armed that evening. Adams was also the only
                   UNITED STATES v. STRAUB                10711
witness who put Straub at the location of the crime. The court
found that, “if a jury believed that Adams lied about this, and
was shifting the blame to Straub for his own actions, it would
seriously weaken the government’s case on counts three and
four,” even under a Pinkerton instruction. The court also
found that “[Misty Dawn] Day’s testimony, by itself, would
not be enough to sustain a conviction on counts three and
four.” These findings of fact suggest that for the government
to grant use immunity for Adams while denying use immunity
to the one witness who could possibly portray Adams as a
perjurer and the true perpetrator of the crime had the effect of
distorting the fact-finding process.

   In addition to considering the fact that Adams was granted
use immunity, we may consider how the prosecution exer-
cised its discretion to provide use immunity and other incen-
tives to secure the testimony of its other witnesses. See
Westerdahl, 945 F.2d at 1087 (observing that the prosecution
had granted use immunity to two witnesses and dropped
charges against a third witness, while denying immunity to a
defense witness who could have contradicted one of the three
prosecution witnesses). The Amended Joint Stipulation of
Facts presents a remarkable picture. Of thirteen witnesses
described, all but one of the prosecution’s twelve witnesses
received either formal immunity, informal immunity, or other
substantial incentives such as cash compensation or a reduc-
tion of sentence in exchange for their testimony. Three gov-
ernment witnesses (David Adams, Alsup, and Smith) received
formal grants of use immunity. Seven government witnesses
(David Adams, Smith, McCord, Center, Weiland, Clark,
Shaw, Jacob Adams, Alsup) appear to have been granted
informal immunity, i.e., they were not charged with any of the
crimes to which they testified at trial, including serious drug
and weapons charges. Six government witnesses (David
Adams, McCord, McFarland, Smith, Mockley, Shaw)
received incentives for their testimony, including one who
was paid $8,300 for providing assistance, and another whose
sentence was reduced from 24 months in prison to three years
10712                   UNITED STATES v. STRAUB
probation. Only one government witness, Misty Dawn Day,
appears to have received no incentives or immunity. All but
one of the eleven government witnesses who received either
immunity or another incentive testified to having committed
crimes involving the sale or manufacture of drugs; several
admitted to sales totaling hundreds of thousands of dollars.

  The only defense witness listed, Mike Baumann, was
denied use immunity.

   [9] The prosecution granted Adams use immunity, and
Adams’ testimony was crucial to the conviction for the
attempted robbery with a firearm. The prosecution denied use
immunity to the one defense witness who could have discred-
ited Adams’ testimony, even though the prosecution claimed
it had no interest in prosecuting that witness. Meanwhile, the
prosecution granted use and informal immunity, gave cash,
and issued sentence reductions to eleven other admitted drug
offenders, all for the purpose of securing evidence against
Straub. We conclude that this exercise of discretion by the
prosecution impermissibly distorted the fact-finding process,
in violation of the Due Process Clause. A trial under these cir-
cumstances is not fundamentally fair. The district court erred
when it denied Straub’s request to compel use immunity.9
   9
     The prosecution also argues that the district court properly refused to
compel use immunity because Straub never formally requested use immu-
nity from the prosecution. As the transcript of the colloquy quoted earlier
demonstrates, Straub did make a formal request to the district judge in the
presence of the prosecution. The prosecution observed the district court
deny the request. It was also equally clear from the prosecution’s support
of the district court’s denial of the request that the prosecution was pre-
pared to deny the request. It would be unnecessarily formalistic for us to
hold that this sequence of events was insufficient to substitute for a direct,
formal request to the prosecutor. Also, both sides agree that the Baumann
situation arose unexpectedly in the middle of trial. While we do not doubt
the prosecution’s claim that securing use immunity is a formal and time-
consuming process, the district court would have had discretion to grant
a continuance.
                   UNITED STATES v. STRAUB               10713
                              III

   The failure to compel use immunity is reviewed for harm-
less error. See Young, 86 F.3d at 949; Lord, 711 F.2d at 891.
Straub argues that we must remand for trial on Counts 1, 3,
4, 5, and 6. Straub has not articulated any specific reasons
why, even if the jury were to hear Baumann’s testimony and
discredit Adams entirely, the jury would not have convicted
on Counts 1, 5, and 6. As for Counts 3 and 4, the only two
counts relating to the armed robbery of Garrett, we find that
the failure to grant use immunity was not harmless. The testi-
mony of David Adams was “crucial” to the prosecution’s case
on Counts 3 and 4. Adams was the only witness who testified
that Straub was armed on the night of the robbery. The district
court also found that the testimony of the prosecution’s other
witness, Misty Dawn Day, “by itself, would not [have been]
enough to sustain a conviction on counts three and four.”
Baumann’s testimony, if believed, would have revealed both
that Adams was dishonest and that he may have actually con-
fessed to the shooting himself. After hearing Baumann’s testi-
mony, it is possible that some jurors would have doubts that
Straub was the shooter and decide to acquit on Counts 3 and
4.

   The government argues that the failure to grant use immu-
nity was harmless as to Counts 3 and 4 because the court gave
a Pinkerton instruction. Thus, the government argues, the jury
could have convicted even if it believed that Adams was the
shooter, as both would be liable as co-conspirators under Pin-
kerton. However, we agree with the district court’s finding:

    In theory, the jury could have convicted Straub on a
    Pinkerton conspiracy theory even if the jurors
    believed Adams was the shooter. . . . Nevertheless,
    the testimony of Adams was important to the prose-
    cution’s case. If a jury believed that Adams lied
    about this, and was shifting the blame to Straub for
    his own actions, it would seriously weaken the gov-
10714              UNITED STATES v. STRAUB
    ernment’s case on Counts 3 and 4. . . . The defense
    could have argued that Adams, not Straub, orches-
    trated the Garrett robbery and shooting, without
    Straub’s knowledge.

   Moreover, as Straub argues, the way the court charged the
jury meant that the case was not effectively tried on the Pin-
kerton theory. The district court instructed the jury on Count
4 before it instructed on Count 3, and the court did not
instruct that Count 4 was a conspiracy count. The court stated
that in order to convict, the government must prove that “the
defendant knowingly and willfully did something or caused
another person to do something that was a substantial step
toward the actual commission of the crime.” In order to con-
vict, the jury would need to believe Adams’s story that Straub
was on the scene and took action to further the crime.

   After the Count 4 instruction, the court then instructed the
jury on Count 3. The first element the government had to
prove in order to get a conviction was that “the defendant is
guilty of the crime charged in Count 4.” The court did give
a Pinkerton instruction that the jury could convict on a con-
spiracy theory on Count 3, if it found that Garrett was “shot
by a person with whom the defendant conspired to commit the
crime described in Count 4.” The problem lies with not
instructing the jury that Count 4 was a conspiracy count;
absent this instruction, it is possible that the jury would not
have convicted on Count 4 unless they found that Straub was
the person who shot Garrett. In order to reach that conclusion,
they would need to believe Adams’ testimony. If the jury did
not convict on Count 4, they could not convict on Count 3
because the first element of Count 3 is a guilty verdict on
Count 4.

  The court mitigated some of this prejudice by stating, after
he had instructed on Count 4 and then Count 3, that the “same
definitions [of the elements of a conspiracy] apply here.” It is
unclear what “here” means and whether the district court was
                    UNITED STATES v. STRAUB                 10715
implying that Counts 3 and 4 were both conspiracy counts.
Convictions cannot rest on ambiguous jury instructions. See
United States v. Washington, 819 F.2d 221, 226 (9th Cir.
1987) (finding that “ambiguous and equivocal jury instruc-
tions” on an important issue constitute reversible error). The
ambiguity in the jury instructions meant that the jury was
probably not able to convict on a Pinkerton theory. The jury
had to find that Straub was a motivating force behind the
shooting, and it probably would not have found this to be the
case if it believed Adams was lying on the stand.

                                IV

   The Fifth Amendment does not create a general right for a
defendant to demand use immunity for a co-defendant, and
the courts must be extremely hesitant to intrude on the Execu-
tive’s discretion to decide whom to prosecute. Alessio, 528
F.2d at 1081-82. Nevertheless, in exceptional cases, the fact-
finding process may be so distorted through the prosecution’s
decisions to grant immunity to its own witness while denying
immunity to a witness with directly contradictory testimony
that the defendant’s due process right to a fair trial is violated.
At Straub’s trial, eleven prosecution witnesses, many of them
serious drug offenders, were granted substantial incentives or
immunity to testify against him. The testimony of one such
witness was crucial to the prosecution’s case for armed rob-
bery. The defense proffered one witness who could directly
contradict a statement made by the prosecution’s key witness,
and if believed, would allow the jury to find that the prosecu-
tion’s witness was a perjurer and possibly the actual perpetra-
tor of the shooting for which the defendant was charged. That
one witness was denied immunity, despite the prosecution’s
insistence that he was not worth prosecuting. Even absent evi-
dence of prosecutorial intent to do so, this course of events
denied Straub a fair trial.

  [10] We reverse the district court’s denial of Straub’s
request to compel use immunity. We affirm the convictions as
10716             UNITED STATES v. STRAUB
to Counts 1, 5, and 6. On remand, the district court should
enter a judgment of acquittal on Counts 3 and 4 unless the
prosecution invokes 18 U.S.C. §§ 6002-6003 to grant use
immunity to Baumann at a new trial, or tries the case without
Adams’s testimony.

 AFFIRMED         in   part,   REVERSED      in   part,   and
REMANDED.
