One evening Emerson Seschillie fired shots at four people, including himself, at a bead stand on the Navajo Reservation. At his jury trial, Seschillie’s sole defense with regard to all the shootings was that he did not intend to pull the trigger of his .357 revolver. Rather, Seschillie argued, each time the gun was fired he and someone else were struggling for control of the gun, causing him to accidentally fire it. We must decide whether the jury conviction should be set aside because (1) the trial court prohibited Seschillie’s expert witness from testifying about the possibility that the gun was accidentally discharged or (2) because the trial court ordered from the courtroom the expert witness Seschillie called to testify to the scientific plausibility of this version of events. We conclude that the conviction should stand.
I. BACKGROUND
Late in the afternoon of September 22, 1999, Bernita Jensen (for clarity “Berni-ta”) and her older sister Rosie Jensen (“Rosie”) stopped by the home of Bernita’s off-again, on-again boyfriend Seschillie. Seschillie was drunk when they arrived. After a brief exchange with Seschillie, Ber-nita and Rosie drove off.
Later in the evening, Bernita and Rosie drove to Bernita’s roadside bead stand, where they joined Bernita’s employee, Gloria Webster. Soon after Bernita and Rosie entered the bead stand, Seschillie drove up, entered the stand and bickered with Bernita. Finally, Bernita said, “Emerson, you are getting to be too mean, you are a little mean. And I don’t want to see you anymore.”
After this exchange, Bernita watched Seschillie leave the bead stand. He returned, however, and yelled, “You don’t love me anymore.” Bernita turned around to see Seschillie pointing a gun at her head. She grabbed the barrel of the gun and pushed it down until Seschillie stiffened. The gun went off, wounding Berni-ta. Bernita then managed to push Seschil-lie’s arm so that the gun pointed up.
At this point, Bernita fled. Rosie and Webster ran to Seschillie. Webster grabbed the gun with one hand and Ses-chillie’s wrist with the other; Rosie also grabbed Seschillie’s wrist. Seschillie continued to hold onto the gun. The gun then went off once, firing a bullet into Rosie’s leg, and then went off once more, striking Seschillie in the leg.
No longer a part of the struggle, the wounded Rosie watched as Webster and Seschillie continued to fight over the gun. Webster and Seschillie fell onto the couch. Webster was on her back and Seschillie was on top of her with the gun pointed at her head. As Webster tried to point the gun away from her face, the gun went off yet again, grazing the side of Webster’s head.
Seschillie then left the bead stand. Rosie and Webster heard another shot and then glass breaking. Seschillie thereupon returned, threatened the two women, and asked about Bernita’s whereabouts. Ses-chillie remained in the bead stand until, about an hour later, the police arrived and arrested him. Seschillie was taken to the *1211 hospital, where it was determined that he had a blood alcohol level of 0.27.
At trial, Seschillie’s defense was that the gun accidentally discharged each time it fired. To bolster this assertion, Sesehillie planned to have his only witness (Sesehillie did not testify), criminologist Ray Gieszl, testify about the possibility of accidental discharge when people are struggling over the possession of a gun. In testimony outside the presence of the jury, Gieszl described several scenarios that can lead to an accidental discharge, including: (1) balance disturbance; (2) startle response; (3) off-hand use (“sympathetic response”); and (4) contested control. 1 Gieszl’s testimony outside the presence of the jury also indicated that each time Sesehillie fired the gun, it was possible that the firing was an accident, because more than one person had a hand on the gun each time.
Following Gieszl’s testimony outside the presence of the jury, the district court held that Gieszl could at trial testify generally about the accidental discharge theories but could not render an opinion as to whether the shootings in this case were accidental, nor could he identify facts in the witnesses’ testimony that were consistent with accidental discharge. At trial, Gieszl testified generally regarding: (1) balance disturbance; (2) startle response; and (3) offhand use. He also explained that each of these three scenarios could be triggered when two or more people fight over control of a gun.
During the trial, the government did not object to Gieszl’s presence in the courtroom. The district court, however, excluded Gieszl from the courtroom.
The jury found Sesehillie guilty of nine counts stemming from these events, including attempted murder. Sesehillie appeals.
II. ANALYSIS
Sesehillie argues that the district court erred both in refusing to let Gieszl opine as to whether the shootings in this case were accidental and by excluding Gieszl from the courtroom when the victims testified regarding the details of the various struggles over the gun. We do not agree with either contention.
A- Exclusion of Expert Opinion
Although the district court allowed Gieszl to testify generally about the accidental discharge theories, it did not allow Gieszl to offer an opinion concerning whether the four shootings at issue in this case were accidental or to comment on the particular facts of the case. Sesehillie urges that because an expert may testify regarding “an ultimate issue to be decided by the trier of fact,” Fed. Rule Evid. 704(a), the district court should have permitted all of Gieszl’s testimony, including his opinion on the ultimate issue in the case: whether the shootings were, in fact, accidental. We review the district court’s determination for an abuse of discretion.
United States v. Ortland,
*1212 In some circumstances, to be sure, an expert may render an opinion on an “ultimate issue.” See generally Fed.R.Evid. 704. We need not decide whether proffering such an opinion would have been proper here. The district court excluded the contested portion of Gieszl’s testimony not only on the ultimate issue theory but also on the alternate rationale that the subject did not require expert illumination. The district court did not abuse its discretion in so ruling. 2
Whether or not expert testimony is appropriate in a particular circumstance is governed by Fed. Rule Evid. 702:
If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise, if (1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case.
(Emphasis added).
The district court concluded that the jury could determine, as a matter of “common sense,” whether the shootings as described by the victims were accidental according to Gieszl’s theories, and would not be assisted in that determination by any specialized knowledge. “A district court does not abuse its discretion when it refuses expert testimony where the subject does not need expert ‘illumination’ and the proponent is otherwise able to elicit testimony about the subject.”
United States v. Ortland,
B. Sequestration of Expert
Seschillie also argues that the district court erred in excluding Gieszl from the courtroom during trial and that Seschillie was prejudiced thereby. Although we conclude that the district court abused its discretion in excluding Gieszl, the error was harmless.
1) The District Court Abused Its Discretion in Excluding Gieszl
Although the government did not object to Gieszl’s presence in the courtroom during the victims’ testimony, the district court, acting sua sponte, ordered Gieszl from the courtroom shortly after the trial commenced. Federal Rule of Evidence 615 (“Rule 615”) governs the exclusion of witnesses from the courtroom:
At the request of a party the court shall order witnesses excluded so that they cannot hear the testimony of other witnesses, and it may make the order of its own motion. This rule does not authorize exclusion of (1) a party who is a natural person, or (2) an officer or employee of a party which is not a natural person designated as its representative by its attorney, or (3) a person whose presence is shown by a party to be essential to the presentation of the party’s cause, or (4) a person authorized by statute to be present.
“The purpose of this rule is to prevent witnesses from ‘tailoring’ their testimony to that of earlier witnesses.”
United
*1213
States v. Ell,
Seschillie argues that Gieszl’s presence was “essential to the presentation of [his] cause” and that Gieszl therefore fell within the third exception to Rule 615. We review the district court’s ruling regarding the applicability of Rule 615(3) for an abuse of discretion.
See Alexander Shokai v. Internal Revenue Service,
In many circumstances, a potential expert witness will be an “essential party” within the meaning of Rule 615(3). The Advisory Committee Notes to Rule 615(3) contemplate as much, stating that the exception includes “an expert needed to advise counsel in the management of litigation.”
See also Alexander Shokai,
We decline to conclude, however, that an expert witness will
always
meet the criteria of Rule 615(3). The reason is simple: “[H]ad the framers intended it, they would have said so, or added a fourth exception.”
Morvant,
*1214
Applying this standard, we conclude that the district court abused its discretion in excluding Gieszl from the courtroom. Seschillie did make the required “fair showing” that Gieszl’s presence was “essential.”
Morvant,
Nor were there any countervailing reasons to sequester Gieszl. Unlike an expert excluded because he is both an expert witness and a fact witness,
see Opus,
The district court dismissed this argument, noting that Gieszl could read the trial transcripts. Trial transcripts are an imperfect substitute for live testimony. The imperfection was patent in this case because some of the witness testimony was demonstrative rather than verbal.
Further, the district court excluded Gieszl primarily because it felt that his presence would send a false message to the jury by creating the impression that the expert has “some added substance.” Rule 615, however, authorizes exclusion “so that [witnesses] cannot hear the testimony of other witnesses,” not for other reasons. Also, the exception contained in Rule 615(3) is for persons “essential to the presentation of the parties’ cause.” If a person meets that criterion, exclusion is “not authorize^].” Rule 615. Excluding Gieszl because of the impression his presence might make on the jury, even though he met the Rule 615(3) exclusion criterion, was an abuse of discretion.
See United States v. Working,
2) The Error was Harmless
Even though excluding Gieszl was improper, we conclude that Seschillie was not prejudiced thereby. 28 U.S.C. § 2111 (error not affecting substantial rights must be disregarded); Fed.R.Crim.P. 52(a) (same). Because the error is not of constitutional magnitude, we apply the harmless error standard for non-constitutional error and “reverse if there is a ‘fair assurance’ of harmlessness, or stated otherwise, unless it is more probable than not that the error did not materially affect the verdict.”
United States v. Morales,
Breneman
noted that “Breneman has made no showing that she was in any way prejudiced by [the Rule 615 error].” As authority for this proposition,
Breneman
relied, in part, on
United States v. West,
Our reading of
Breneman
and
Alexander Shokai
is reinforced by several considerations. First, in
Ell,
Finally, placing the risk of equipoise on the government is consistent with the post
Breneman
and
Alexander Shokai
precedent of
O’Neal v. McAninch,
In answering the dispositive question, whether the error substantially influenced the jury’s decision, we give particular scrutiny to some Rule 615 violations. For example, when a district court fails to exclude a fact witness, and the witness has an opportunity to hear relevant fact testimony of other witnesses, the government may have difficulty convincing us that the resulting error was harmless. As we stated in Ell:
It may be impossible to tell how a witness’ testimony would have differed had the defendant’s motion to exclude been granted. Therefore, we hold that when a court fails to comply with Rule 615, prejudice is presumed and reversal is required unless it is manifestly clear from the record that the error was harmless or unless the prosecution proves harmless error by a preponderance of the evidence. See United States v. Castillo,615 F.2d 878 , 883 (9th Cir.1980) (violation of evidentiary rule judged by “more probably than not harmless” standard).
The rationale which compels particular scrutiny in that scenario, however, does not apply where, as here, the court
does
exclude an expert witness, albeit improperly. Once witness influence takes place, it “may be impossible to tell how a witness’ testimony would have differed had the defendant’s motion to exclude been granted.”
Ell,
*1217
Tuning to the current case, we can say with “fair assurance” that the error was harmless.
Mitchell,
We also reject Seschillie’s vague, post-hoc argument, advanced for the first time in his reply brief, that Gieszl’s presence was essential because he could have assisted Seschillie’s counsel in performing cross-examination. Generally, arguments not raised in the opening brief are deemed waived.
United States v. Alexander,
A comparison to
Malek
is instructive. In that arson case, the court found that the improper exclusion of a fire expert witness contributed to prejudice because the expert could have rendered useful advice regarding cross-examination.
Here, Seschillie has not identified any missed avenues of cross-examination which would have been potentially fruitful. Absent any such indication, we can say with fair assurance that the lack of opportunity to assist in cross-examination was harmless.
See Opus,
CONCLUSION
For the reasons stated above, we AFFIRM.
Notes
. Gieszl further explained the theories he described as follows: (1) Balance disturbance: ‘ When someone loses his balance, there is a muscle response initiated and he “will grip or crunch down on the firearm while pulling the trigger.” (2) Startle response: When someone is surprised his physical reaction is to clench his hands. (3) Off-use hand or sympathetic response: Due to an ‘‘interconnective neural response between the two limbs,” if a person grips or grasps something with the hand not holding the firearm he will sometimes involuntary pull the trigger with the other hand. (4) Contested control: A person will sometimes involuntary fire a gun when two or more people are struggling for control of the gun.
. Because we conclude that this basis for exclusion was not an abuse of discretion, we do not consider the district court’s other stated reasons for exclusion.
. A different standard applies when a parly requests an exclusion and a district court fails to exclude a witness under Rule 615 if no exception applies. Because Rule1 615 states that the court, at the request of a party,
shall
order witnesses excluded, “[t]he rule makes the exclusion a matter of right and the decision is no longer committed to the court's discretion as it once was.”
United States v. Brewer,
. We do not necessarily suggest that
Breneman
and
Alexander Shokai
should indeed be distinguished as civil, rather than criminal cases. To the contrary, the Supreme Court has indicated that the burden of persuasion in harmless error analysis is similar in both civil and criminal cases.
O’Meal v. McAninch,
. Although
Payton
and
O’Neal
evaluated harmless error in the context of a habeas case, the reasoning applies to a review of nonconstitutional error on direct appeal. In both circumstances, harmless error analysis is a legal rather than factual determination, unaided by burdens and presumptions. Moreover, in both circumstances we apply the harmless standard announced in
Kotteakos v. United States,
. The three victims testified on October 12, 2000 and October 13, 2000 but Gieszl did not take the stand until October 17, 2000. Compare Malek, 994 F.2d at 53-54 (excluding expert contributed to prejudice when expert given only 10 minutes to review relevant trial transcripts).
