                          In the
 United States Court of Appeals
              For the Seventh Circuit
                       ____________

No. 05-4309
UNITED STATES OF AMERICA,
                                           Plaintiff-Appellee,
                             v.

JOHNNY J. JACKSON,
                                       Defendant-Appellant.
                       ____________
         Appeal from the United States District Court
               for the Central District of Illinois.
         No. 04 CR 10058—Joe Billy McDade, Judge.
                       ____________
   ARGUED JANUARY 4, 2007—DECIDED MARCH 12, 2007
                   ____________


 Before POSNER, RIPPLE, and WILLIAMS, Circuit Judges.
  WILLIAMS, Circuit Judge. In this appeal we consider the
admissibility of evidence of an out-of-court experiment
conducted in order to rebut a criminally accused’s ver-
sion of events. Johnny Jackson was tried and convicted of
being a felon in possession of a firearm. One of the key
components of his defense was that at the time he was
alleged to have committed a shooting and to have pos-
sessed a gun, he was actually picking up his girlfriend
from work. To rebut the alibi, the government sent a
deputy United States Marshal to see how long it would
take to drive from the scene of the shooting to the girl-
friend’s place of employment. The Marshal testified that
his drive time was short, which provided the basis for the
2                                               No. 05-4309

prosecutor to argue in closing that Jackson could have
committed the shooting and still had time to pick up his
girlfriend. On appeal, Jackson challenges the admission of
this evidence, but since the experiment was offered in
rebuttal and was conducted under substantially similar
circumstances as Jackson’s drive, we find that the evi-
dence was properly admitted. Jackson also contends that
the district court gave an improper jury instruction and
that that the firearm he possessed did not affect inter-
state commerce, as the statute requires, but we reject
these arguments as well and affirm on all grounds.


                   I. BACKGROUND
   The indictment charges Jackson with possessing a
firearm “[o]n or about July 12, 2004, through July 15,
2004,” but to understand what took place at that time
we must first travel back a month earlier, to June 19,
2004. On that date Jackson and his nephew, Jarvis
Jackson, confronted Tarus Watkins and Watkins’s brother,
Donny Richardson, in Peoria, Illinois, demanding money
owed from a dice game. A shootout between Jarvis and
Donny occurred, leaving Jarvis dead, and both Donny
and the defendant wounded.1 The government contends
that this incident, in which the defendant’s nephew was
shot to death by Tarus Watkins’s brother, created a motive
for the defendant to shoot at Tarus Watkins a month later.
  That shooting occurred on July 12, 2004. Watkins was
the only person at trial to testify about the incident. He
stated that “shortly after 2:00 p.m.” he left a store on his
way home, and that after several blocks of walking the
defendant peeked out from behind a church and then ran


1
  Donny Richardson was later prosecuted and convicted for his
role in the shooting.
No. 05-4309                                                   3

into the street firing a gun at him. Watkins was not hit,
but he heard three gunshots and saw a black, short-nosed
revolver in the defendant’s hand. He fled and called the
police; a dispatch call from police headquarters was
placed at 2:34 p.m. sending officers to the scene. Jackson
was arrested in his car three days later on July 15;
authorities recovered a similar gun on the ground outside
the car.2
  The defense tried to cast doubt on Watkins’s account of
the July 12 shooting by introducing testimony from Jack-
son’s girlfriend, Unity Nelms, who stated that Jackson
usually picked her up from work. That day, she called him
at his house at 1:40 or 1:45 p.m. and asked him to pick
her up at 2:30 p.m. Her timecard shows that she punched
out at 2:43 p.m., and she testified remembering that
Jackson was there waiting for her at that time. She also
testified that in her own experience, the drive from Jack-
son’s house to her work took between 20 and 30 minutes.
The defense’s theory was that Jackson could not have
shot at Watkins shortly after 2:00 p.m., because he
would have been on his way to pick up Nelms.
  That evening, after hearing Nelms’s trial testimony, the
government sent a deputy U.S. Marshal to drive from the
scene of the shooting—which is five blocks away from
Jackson’s house, in the opposite direction from Nelms’s
work3—to the restaurant where Nelms worked. The next
morning as part of the government’s rebuttal case, the


2
  The gun was actually discovered outside the passenger’s side
of the car; Jackson was in the driver’s seat and a friend was in
the passenger’s seat. At trial the parties hotly disputed the
circumstances surrounding the recovery of the gun, but that
dispute is not relevant to this appeal.
3
   In other words, the simulated drive was actually five blocks
longer than the drive between Jackson’s house and Nelms’s place
of employment.
4                                                No. 05-4309

marshal testified that the drive, which was 7.4 miles long,
took twelve minutes. He testified that he selected what
he knew from familiarity with the area to be the shortest
route, that he was stopped by red lights at over half of
the stoplights, that he conducted the experiment shortly
after 7:00 p.m.,4 and that for one portion of the drive he
exceeded the speed limit in order to keep up with the
flow of traffic. The defense, which objected to the intro-
duction of the evidence, cross-examined the marshal,
attacking his experiment because it was not based on the
specific route that Jackson used that day, because traffic
patterns would vary between night and day, and because
his speeding would have affected the overall drive time.


                      II. ANALYSIS
A. Evidence of driving experiment
  On appeal, Jackson first contends that the district
court abused its discretion by admitting the marshal’s
testimony about the driving experiment. He concedes that
he is a “felon” under 18 U.S.C. § 922(g)(1), but contends
that he did not possess a firearm, and the evidentiary
challenge goes to that element of the offense. Although he
does not point to this provision, our review is governed by
Federal Rule of Evidence 403, which renders inadmissible
evidence whose probative value is outweighed by the
danger of unfair prejudice. See United States v. Russell,



4
  At oral argument in this court, counsel for the government
stated that the decision to conduct the experiment came at the
close of the second-to-last day of trial in response to Nelms’s
unanticipated testimony of driving time. The short amount of
time available to the government to refute Nelms’s testimony
accounts for the time of day at which the experiment was
conducted.
No. 05-4309                                                 5

971 F.2d 1098, 1106 (4th Cir. 1992); Kenneth S. Broun,
McCormick on Evidence § 202 (6th ed. 2006).
  Evidence of experiments is most commonly used in the
context of products liability law, where recreations of
accidents, explosions, and product malfunctions are now
common. See, e.g., Buscaglia v. United States, 25 F.3d 530,
533 (7th Cir. 1994); Carey ex rel. Carey v. Hy-Temp Mfg.,
929 F.2d 1229, 1235 n.2 (7th Cir. 1991). Because this type
of evidence can be quite persuasive, in order to avoid
unfair prejudice, the conditions under which an experi-
ment is performed must be “substantially similar” to those
surrounding the simulated event. Mihailovich v. Laatsch,
359 F.3d 892, 908 (7th Cir. 2004). This is a flexible require-
ment: “substantially similar” does not mean “identical,”
and dissimilarities can be explored on cross-examination.
See Buscaglia, 25 F.3d at 533. In other words, as a general
matter, “dissimilarities between experimental and actual
conditions affect the weight, not the admissibility of the
evidence.” 33A Fed. Proc., L. Ed. § 80:254 (2006).
  Although there is little circuit precedent on the subject,
the substantially similar requirement also applies in the
criminal context. See United States v. Baldwin, 418 F.3d
575, 579-81 (6th Cir. 2005); United States v. Birch, 39 F.3d
1089, 1092-93 (10th Cir. 1994); Russell, 971 F.2d at 1105-
06. Whether in a criminal case or a civil one, however, the
requirement’s application always depends on the purpose
for which the experiment is introduced. See Jones v. Ralls,
187 F.3d 848, 853 (8th Cir. 1999). So if the purpose is to
recreate an event, the timing and physics of which are
critical, courts will only admit evidence of experiments
that are conducted under nearly identical conditions as
the actual event. Broun, McCormick § 202. For instance,
in Jackson v. Fletcher, 647 F.2d 1020, 1026-28 (10th Cir.
1981), the district court erred by admitting evidence of
an experiment purporting to recreate an accident between
a car and a truck in order to determine the precise speed of
6                                              No. 05-4309

the truck at the time of collision. The court held that
since the simulation truck was empty whereas the actual
truck carried a full load (creating a weight differential of
37,000 pounds), and the two trucks were different model
years, the experimental conditions were not substan-
tially similar to the actual ones. Id.
  By contrast, where the purpose of the experiment is not
to recreate events but simply to rebut or falsify the
opposing party’s sweeping hypothesis, the substantial
similarity requirement is relaxed. Broun, McCormick
§ 202. In Osborne v. United States, 542 F.2d 1015, 1019-20
(8th Cir. 1976), the most similar federal circuit case on
point, the defendant, accused of robbery, contended that
he could not have committed the crime in the early
afternoon because he applied for unemployment benefits
at 2:00 p.m. in an office 23 miles away from the scene of
the crime. In rebuttal, an FBI agent testified that he had
driven from the crime scene to the unemployment office
and showed, based on the drive time, that it was possible
for the defendant to have committed the robbery and
driven to the office, still arriving by 2:00. The appellate
court affirmed the district court’s admission of the evi-
dence, holding that “the experiment did not purport to
recreate events as they actually occurred on the day of
the robbery but rather established whether it was physi-
cally possible for [the defendant] to have traversed the
distance between the stash point and the railway office
in the time allowed.” Id. at 1120. Other circuits have also
concluded that dissimilarities of the type Jackson points
out can be identified in cross-examination to weaken
the evidence’s impact, but they do not bar its admission
in the first place. See Birch, 39 F.3d at 1092-93; Russell,
971 F.2d at 1105-06; United States v. Metzger, 778 F.2d
1195, 1204-05 (6th Cir. 1985); cf. Baldwin, 418 F.3d at
581 (although district court did not abuse discretion in
No. 05-4309                                                    7

excluding evidence of experiment, it would not have abused
discretion had it admitted the evidence).5
  The case here is quite similar to Osborne. The govern-
ment was attempting to cast doubt upon the defense’s
implication that Jackson could not have committed the
shooting sometime after 2:00 p.m. and still had time to
pick up his girlfriend at 2:43 p.m. (Since Nelms testified
that the drive from Jackson’s home to her work takes
between 20 and 30 minutes, this is not the strongest alibi
to begin with.) The government was not trying to recreate
Jackson’s actual drive. If, as the evidence tended to
show, the drive could be completed in as little as 12
minutes, then Jackson could potentially have fled the
scene of the shooting as late as 2:31 p.m., and could
therefore have committed the shooting (and possessed
the handgun) shortly after 2:00 p.m. The jury was permit-
ted to weigh this evidence and consider the weaknesses
elicited on cross-examination. If jurors thought the condi-
tions of the experiment too dissimilar, they could give
the evidence little weight. Although an ideal test would
have recreated the traffic conditions, route, and time of
day under which Jackson performed the drive, given the
limited purpose for which the experiment was offered, the
experiment was substantially similar to actual conditions.
Had the testimony been offered in the government’s case-
in-chief, rather than in rebuttal of the defendant’s story,
a different result might be warranted. However, on the


5
   State courts confronting evidence of this type of experiment
have reached similar results. See, e.g., State v. Don, 318 N.W.2d
801, 805 (Iowa 1982) (evidence of informal driving experiment
to undercut murder alibi admitted); People v. LeMasters, 666
P.2d 573, 576-77 (Colo. App. Ct. 1983) (burglary alibi); State v.
McFadden, 455 N.E.2d 1, 3 (Ohio Ct. App. 1982) (same); People
v. Terry, 113 Cal. Rptr. 233, 241-42 (Cal. Ct. App. 1974) (same).
8                                               No. 05-4309

facts of this case, the district court did not abuse its
discretion in admitting the evidence.


B. Unanimity instruction
  Jackson next argues that the jury’s verdict may not
have been unanimous because the district court provided
only a general unanimity instruction. He points out that
when the district court explained to the jury the elements
of 18 U.S.C. § 922(g)(1), and specifically the element of
“possession” of a firearm, the court stated that the jury
must find that Jackson possessed a firearm on “July 12
and/or July 15.”6 His fear is that some of the jurors
might have found that he possessed a gun on July 12th
and some on July 15th—which would not, he claims, be a
unanimous verdict as to the element of possession. The
only way to prevent this possibility, Jackson says, would
have been a specific instruction admonishing the jury
that it must unanimously find that he possessed the gun
either on July 12 or on July 15, rather than a general
instruction that the jury must reach a unanimous verdict.
  Since Jackson did not object to the district court’s
instruction or proffer his own, our review is only for plain
error. United States v. Peters, 435 F.3d 746, 754 (7th Cir.
2006). It is a rare case in which an improper jury instruc-
tion will justify upsetting a criminal conviction. Id. When
a defendant fails to object to the trial court’s general
unanimity instruction, that instruction will usually suffice
and no specific instruction will be needed. See United
States v. Cherif, 943 F.2d 692, 701 (7th Cir. 1991); United
States v. Williams, 737 F.2d 594, 613-14 (7th Cir. 1984);



6
  Again, July 12 was the date of the shooting and July 15 the
date of Jackson’s arrest.
No. 05-4309                                                 9

United States v. Pavlovski, 574 F.2d 933, 936 (7th Cir.
1978).
  We find no error here, let alone one that is plain. Una-
nimity can indeed present a concern where an indictment
includes in a single count two offenses that could be
charged separately. For instance, in United States v.
Payseno, 782 F.2d 832 (9th Cir. 1986), a case that Jackson
cites, the defendant’s indictment for extortion charged, in
a single count, three separate extortionate acts against
three victims over the course of eight months. The appel-
late court found that jurors might not have understood
that they needed to find unanimously that the defendant
was guilty of one of the three acts, and therefore held
that the district court’s failure to give a specific unanimity
instruction was plain error. Id. at 836-37. But see United
States v. Anguiano, 873 F.2d 1314, 1319-20 (9th Cir. 1989)
(emphasizing that a general unanimity instruction is
sufficient in the absence of a complex set of facts or a
broad and ambiguous indictment that could easily con-
fuse a jury as to the need for unanimity).
  But here the indictment charged not multiple offenses
under one count of being a felon in possession, but a single
course of illegal conduct that spanned three days. See
United States v. Fleischli, 305 F.3d 643, 658 (7th Cir. 2002)
(“Possession of a firearm is a continuing offense which
ceases only when the possession stops.”); see also United
States v. Buchmeier, 255 F.3d 415, 424-25 (7th Cir. 2001)
(discussing distinction between continuing course of
conduct and multiple offenses). If half of the jurors found
that Jackson possessed the gun on July 12 and half
found that he possessed it on July 15, the jury would still
be unanimous that he possessed a gun between July 12 and
July 15—which is exactly what the indictment charged.
See R.20, at 1 (“On or about July 12, 2004 through July 15,
2004 . . . the defendant herein, did knowingly possess a
10                                                    No. 05-4309

firearm.”); see also Williams, 737 F.2d at 613-14 (empha-
sizing sufficiency of clear indictment coupled with general
unanimity instruction); Anguiano, 873 F.2d at 1320
(same). Indeed, to convict Jackson on two separate counts
of being a felon in possession, the government would have
had to prove that he lost possession of the gun at some
point between the two charged dates. See United States
v. Conley, 291 F.3d 464, 470-71 (7th Cir. 2002).7
   The fact that this case does not present two offenses
listed under one count, coupled with our rule that a
general unanimity instruction is usually enough in the
absence of an objection or a tendered instruction,
Pavlovski, 574 F.2d at 936, dooms this claim.


C. Interstate commerce
   Finally, Jackson argues that his possession of the
firearm did not affect interstate commerce. He does not
dispute the evidence that shows that the gun was manu-
factured in Brazil, entered the United States in Miami,
and then traveled to Illinois, and he acknowledges that
this movement in interstate commerce is all the Su-
preme Court requires under the statute. Scarborough v.
United States, 431 U.S. 563 (1977); see United States v.
Williams, 410 F.3d 397, 400 (7th Cir. 2006). Rather, he


7
   In the context of 18 U.S.C. § 922(g)(1), we note that other
circuits have concluded that no specific instruction is required to
ensure juror unanimity as to which of two firearms a felon
possessed, so long as the jurors agree that he possessed a
firearm. See United States v. DeJohn, 368 F.3d 533, 540-42 (6th
Cir. 2004); United States v. Verrecchia, 196 F.3d 294, 298-301 (1st
Cir. 2001); cf. United States v. Lee, 317 F.3d 26, 38 (1st Cir. 2003)
(no need for unanimity as to which 15 of 22 illicit credit cards
the defendant possessed, so long as the jury agreed that he
possessed 15 illicit cards).
No. 05-4309                                           11

raises this issue to preserve the possibility of further
appellate review. Only the Supreme Court can reverse
itself, so we need not discuss this contention further.


                 III. CONCLUSION
 For these reasons, the judgment of the district court is
AFFIRMED.

A true Copy:
      Teste:

                      ________________________________
                      Clerk of the United States Court of
                        Appeals for the Seventh Circuit




                  USCA-02-C-0072—3-12-07
