United States Court of Appeals
                            FOR THE EIGHTH CIRCUIT
                                    ___________

                                    No. 06-3820
                                    ___________
United States of America,                 *
                                          *
             Appellee,                    *
                                          *   Appeal from the United States
      v.                                  *   District Court for the
                                          *   Western District of Missouri.
Michael R. Burns,                         *
                                          *
             Appellant.                   *
                                    ___________

                              Submitted: June 14, 2007
                                 Filed: August 1, 2007
                                  ___________

Before LOKEN, Chief Judge, ARNOLD and COLLOTON, Circuit Judges.
                              ___________

ARNOLD, Circuit Judge.
      A jury convicted Michael Burns of one count of conspiring to distribute
500 grams or more of methamphetamine, see 21 U.S.C. §§ 841(a)(1), (b)(1)(A), 846,
and two counts of distributing 50 grams or more of the drug, see 21 U.S.C.
§ 841(a)(1), (b)(1)(B). After the district court1 imposed a sentence of three concurrent
terms of 360 months' imprisonment, we affirmed the conviction and remanded the
case for resentencing. United States v. Burns, 

(8th Cir. 2005). On
remand, Mr. Burns moved for a new trial under Federal Rule of Criminal Procedure



      1
        The Honorable Richard E. Dorr, United States District Judge for the Western
District of Missouri.
33, and the district court denied the motion without an evidentiary hearing. Mr. Burns
appeals and we affirm.
                                           I.
       Mr. Burns claims that newly discovered evidence shows that Missouri Highway
Patrol chemist Matthew Barb perjured himself when he testified at trial about the
quantity of drugs put in evidence against Mr. Burns. After Mr. Burns's trial,
investigators discovered that Mr. Barb was a drug addict who had been pilfering drugs
from lab samples, and Mr. Barb later pleaded guilty to stealing amphetamines from
the Highway Patrol lab where he worked. Mr. Burns thus speculates that Mr. Barb
may have tampered with the evidence that was introduced at Mr. Burns's trial and
contends that the revelations about Mr. Barb's activities entitle him to a new trial.


       Mr. Burns maintains first that he is entitled to a new trial because Mr. Barb's
testimony tainted his original trial. As support for this contention, Mr. Burns relies
on Mesarosh v. United States, 

(1956). Mesarosh did not involve a new
trial motion: While that case was pending in the Supreme Court, the government itself
brought to the Court's attention new evidence showing that a crucial government
witness who had testified against the criminal defendant had not told the truth in
numerous other proceedings against other individuals in which he had testified "in the
same field of activity," i.e., as a government informant paid to infiltrate the
Communist Party. 

10. Relying on its supervisory authority over lower
federal courts, the Court held that the defendant was entitled to a new trial because the
witness's repeated untruthfulness (whether deliberate or the result of a psychiatric
condition) had "tainted" the defendant's conviction. 

14.


      The Mesarosh holding has no application to the present case because there is
no evidence whatever that Mr. Barb was a practiced perjurer or suffered from some
disqualifying mental condition. There was, moreover, no evidence that he perjured
himself in Mr. Burns's trial. The worst that might be said with any confidence about

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Mr. Barb's testimony is that he did not disclose his drug habit or his thefts. But a
failure to disclose matter that might be useful for impeachment purposes is not
perjury. Mr. Burns offers no evidence that contradicts any particular answer that
Mr. Barb gave at trial. We thus have no reason to believe that Mr. Burns's trial was
tainted in the way that the trial in Mesarosh was. The newly discovered information
about Mr. Barb's criminal activities could have been used to impeach his general
credibility, but that is a different matter entirely.


                                          II.
       Mr. Burns also contends that he should get a new trial because of newly
discovered evidence. To be eligible for a new trial on this basis, he must establish,
among other things, that the new evidence "would likely produce an acquittal."
United States v. Barajas, 

, 1026 (8th Cir. 2007). Here, the new
evidence is admissible only for impeachment purposes, and this kind of evidence is
rarely sufficient to entitle a defendant to a new trial. See 

. We
see no reason to think that the impeachment evidence would have produced an
acquittal on any count or a jury finding that the conspiracy involved less than
500 grams of methamphetamine or that the distribution counts were based on the
transfer of less than 50 grams of drugs.


      The case against Mr. Burns, including the amount of drugs with which he was
involved, was overwhelming, and it suffices to mention here only some of the most
incriminating evidence against him. On two occasions, Mr. Burns negotiated with an
undercover officer and sold the officer an ounce of methamphetamine each time.
Other witnesses testified that Mr. Burns was involved in a conspiracy to sell
methamphetamine: one of them, co-defendant Howard Neustel, testified in detail
about Mr. Burns’s criminal activities and kept ledgers recording the large amounts of
methamphetamine that he bought from Mr. Burns and the sums that he paid for them.
Mr. Burns does not dispute that methamphetamine was seized from him and his

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criminal associates. We note, moreover, that if Mr. Barb stole methamphetamine from
the drugs relevant to Mr. Burns's case, that could only have reduced, not increased, the
amount of drugs attributable to him.


                                          III.
      Mr. Burns offered the district court an affidavit from juror Patricia Kassab as
evidence that she would have voted to acquit him had the newly discovered evidence
been introduced at trial. In her affidavit, Ms. Kassab attested that had she known
during the trial about Mr. Barb’s drug addiction and theft "it would have caused [her]
reasonable doubt as to the proof of the amount and weight of the methamphetamine
offered into evidence in Mr. Burns’s case."


       Federal Rule of Evidence 606(b) generally prohibits a juror from testifying
about her or other jurors' mental processes during jury deliberations. We think that
the principle behind this prohibition extends to testimony about what those mental
processes would have been had the evidence at trial been different. Cf. Capps v.
Sullivan, 

, 262-63 (10th Cir. 1990). More fundamentally, the question
of whether different evidence would have produced a different result must be
answered by asking what a reasonable jury would likely have done with that evidence
before it, not what some particular juror or jurors would have done. We therefore
decline to give Ms. Kassab's affidavit any weight.


                                          IV.
       Mr. Burns also contends that the district court should have given him an
evidentiary hearing before making a decision on his motion for a new trial. When
ruling on a new trial motion based on newly discovered evidence, the "district court
has broad discretion in deciding whether an evidentiary hearing is necessary." United
States v. Provost, 

, 619 (8th Cir. 1992), cert. denied, 

                                          -4-
(1993). We hold that the district court did not abuse its discretion here because Mr.
Burns failed to show that his case involved any "exceptional circumstances" that
might have required a hearing. See 

Burns never established how a
hearing was at all likely to produce the type of evidence that would entitle him to a
new trial.


      Affirmed.
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