¶1 Defendant and Appellant Philip Bryson Grimshaw (Grimshaw) appeals the

Judgment issued by the Eighth Judicial District Court, Cascade County, on April 18, 2018,

following his conviction of Sexual Intercourse Without Consent, a felony, in violation of

§ 45-5-503, MCA.

¶2 We address the following restated issue on appeal:

Whether the District Court abused its discretion and compromised Grimshaw’s

right to a fair trial by allowing expert witness testimony regarding statistics about

false reports of sexual assault.

¶3 We reverse and remand for a new trial.

FACTUAL AND PROCEDURAL BACKGROUND

¶4 Grimshaw is step-cousins with T.G. The two are around the same age and were

close friends, particularly in the years after Grimshaw’s father died. Grimshaw developed

romantic feelings for T.G., which he expressed to her. She informed Grimshaw they could

not be together because they are cousins. The two remained close friends, however.

¶5 Shortly before midnight on November 10, 2016, T.G. got off work. She had been

texting with Grimshaw throughout the day and went to Grimshaw’s house in Great Falls

around 1:00 a.m. on November 11, 2016, after Grimshaw texted her and asked if she

wanted to “come party.” T.G. went to the house and joined in playing drinking games with

around seven or eight other people. After a while, T.G. heard yelling and glass break. She

discovered Grimshaw in the bathroom with his hand bleeding because he had punched a

picture on the wall. Grimshaw kicked everyone else out of the party and went for a drive

with T.G. Grimshaw and T.G. took some alcoholic beverages from the house and drove to

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the gravesite of Grimshaw’s father, an activity they had done many times before. At the

gravesite, the two sat on the grass and talked while drinking and smoking. They left the

cemetery around 4:00 a.m. and continued to drive around while drinking and smoking

marijuana. The two arrived at T.G.’s house around 6:00 a.m. on the morning of

November 11.

¶6 After arriving at T.G.’s house, Grimshaw and T.G. briefly hung out on the couch

before T.G. gave Grimshaw a pillow and blanket and went upstairs to go to bed. At 6:27

a.m., Grimshaw, who was still on the couch downstairs, texted T.G., “Goodnight

beautiful.” T.G. responded “Goodnight love ” before Grimshaw texted back,

“Goodnight darlin can I come cuddle with you? I mean if it’s not to [sic] much.” T.G.

testified she did not respond because she had already fallen asleep.

¶7 The parties disagree about what happened next; however, it is undisputed Grimshaw

and T.G. had sex. At trial, T.G. testified the first thing she remembered upon waking up

was Grimshaw pulling down her pants and penetrating her anus with his penis. T.G. told

Grimshaw “no,” before Grimshaw flipped her over and penetrated her vagina with his

penis. T.G. testified she did not say anything after that because Grimshaw pinned her to

the bed with his hand around her throat while he had sex with her. T.G. testified she

blacked out for a moment and regained consciousness as Grimshaw grabbed the back of

her head and put his penis in her mouth. T.G. immediately took Grimshaw’s penis out of

her mouth and the two said nothing to each other. Grimshaw then passed out. After

Grimshaw passed out, T.G. gathered her clothes and went downstairs where she fell asleep

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on the couch. T.G. awoke to Grimshaw coming down the stairs. Grimshaw said he was

going outside to smoke a cigarette and left the house.

¶8 After he left, Grimshaw texted T.G. and the two had the following text message

exchange:

Grimshaw: I’m sorry about last night. I love you darling. I know you

probably never want to talk to me after what happen.

T.G.: It’s ok, I love you to. Where did you go?

Grimshaw: I feel like i had to leave

T.G.: Um ok.

Grimshaw: So I started walking home

T.G.:

Grimshaw: Do you hate me?

T.G.: Did I say that?

Grimshaw: Just making sure.

T.G.: Fucked up though.

Grimshaw: I feel ya

T.G.: Yep.

Grimshaw: I’m still hella drunk

T.G.: Jeez

Grimshaw: Yeah I love you.

T.G.: I love ya to.

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T.G. testified it was “[f]ucked up” both because they were cousins and because Grimshaw

had raped her.

¶9 T.G. did not immediately report the rape. She testified she was scared, uneasy, and

unsure what to do because Grimshaw was family and her best friend. On November 21,

2016, T.G. went to the hospital due to a migraine headache. While at the hospital, T.G.

told her mother about the rape and was examined by a sexual assault nurse. At the hospital,

T.G. told the nurse and a responding police officer what happened with Grimshaw on the

morning of November 11. A few days later, T.G. was interviewed by Detective Noah Scott

at the Great Falls Police Department where she told him the story of what happened on the

morning of November 11.

¶10 Grimshaw’s account of the events of November 11 differed from T.G.’s during an

interview he gave to Detective Scott and Detective Adam Price of the Great Falls Police

Department on November 28, 2016. Grimshaw first told the detectives he blacked out from

drinking on the night of the incident and remembered little, but could have had sex with

T.G. After Detective Scott showed Grimshaw pictures of the text conversation between

Grimshaw and T.G., Grimshaw stated he apologized to T.G. after she told him they had

sex, but he had no recollection of having sex with T.G. Grimshaw told the detectives “it

might have been a little, kind of, rape deal.” He told the detectives all he remembered was

going up to cuddle with T.G. in her bed. He said she was awake but intoxicated. He said

the next thing he remembered was waking up alone in T.G.’s bed, and he realized what

happened because his clothes were scattered everywhere. Grimshaw said he went

downstairs, woke T.G. up, apologized for having sex with her, and left.

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¶11 When asked by the detectives what, looking back, he felt the incident was,

Grimshaw responded “Rape. I mean . . . yeah, I did something that she didn’t want, and I

did it forcibly.” After this statement, Grimshaw told the detectives he was going to be

truthful and he did remember a lot of what happened that night. He said he remembered

going upstairs to cuddle with T.G. in her bed, starting to feel her up, being felt up by T.G.,

and then having sex. Grimshaw said he thought T.G. wanted to have sex with him at the

time and he did not forcibly remove her clothes or have sex with her while she was not

awake. Grimshaw said he realized after the fact that T.G. did not want to have sex, as she

had previously told him they “could never be anything, could never do anything” because

they were cousins. Grimshaw was arrested at the end of this interview and charged with

one count of sexual intercourse without consent.

¶12 Before the first trial setting, the State filed a Notice of Expert Witness and indicated

Dr. Sheri Vanino would “testify as to the behavior(s) of rape victims, including but not

limited to the actions of rape victims after being raped, such as delayed disclosures and

continued contact with the perpetrator following the rape[.]” After receiving this notice,

Grimshaw moved to continue the trial so he could find a rebuttal expert witness to testify

at trial, which the District Court granted. Grimshaw thereafter filed a Notice of Rebuttal

Expert Witness, indicating Dr. Bowman Smelko would “testify in rebuttal on the same

topics as the State’s expert[.]”

¶13 The matter went to trial in September 2017. Grimshaw contended at trial that the

sex was consensual and T.G. falsely accused him of rape because she was ashamed about

having sex with her cousin. After Detective Scott, sexual assault nurse Jessica Bray, T.G.,

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and Angela Grimshaw testified, the State called Dr. Vanino. Dr. Vanino testified as a

“blind expert”—testifying generally to behaviors exhibited by victims of sexual assault

including delays in disclosure, not specifically to the facts of the present case. While

testifying to these behaviors, Dr. Vanino stated one of the popular misconceptions was

“that women tend to run around and falsely accuse people of rape, or cry rape all the time,

which is really not supported. And so, most women don’t report.” Counsel for Grimshaw

objected to Dr. Vanino “talking about statistics or what’s common or what’s not common

on false reports,” arguing such testimony was barred by State v. Brodniak, 221 Mont. 212,

718 P.2d 322 (1986). The District Court overruled Grimshaw’s objection, finding that as

long as Dr. Vanino’s “comments are with regard to the myths, I’ll allow the witness to

testify.”

¶14 Dr. Vanino continued testifying about the misconceptions surrounding false reports

and then the State asked a question about what the research supports regarding delayed

disclosures. Before answering the State’s question, Dr. Vanino expressed she was

confused about whether she was allowed to talk about statistics. Grimshaw reiterated his

objection to testimony about statistics pursuant to Brodniak and M. R. Evid. 702. The

District Court again overruled Grimshaw’s objection, noting Grimshaw had a rebuttal

expert and the issue would “come[] down to a battle of the experts[.]” Dr. Vanino then

testified only 16 to 20 percent of sexual assault survivors ever tell anyone. On

cross-examination, Dr. Vanino testified about 19 percent of sexual assault victims fight

back and again that only 16 to 20 percent of victims report. On re-direct, the State asked

Dr. Vanino about false reporting statistics. Dr. Vanino testified between “two and eight

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percent of sexual assault cases end up to be false reporting,” and noted false reports

typically included details consistent with the other rape myths to which she had previously

testified.

¶15 Grimshaw called Dr. Smelko as his rebuttal expert. Dr. Smelko acknowledged the

validity of the statistics as presented by Dr. Vanino, but testified to the limited sample sizes

of the studies and the difficulty in verifying false reporting statistics. Dr. Smelko testified

“the [two to eight] percent, I think, is pretty recognized as the number if we’re considering

those who make false allegations.”

¶16 During its closing argument, the State emphasized the statistical testimony of

Dr. Vanino and Dr. Smelko, telling the jury “you heard from Dr. Vanino, and Dr. Smelko

agreed, incidents of false reporting is two percent to eight percent. And it’s usually from

someone with something to gain or someone who’s, as Dr. Vanino said, truly psychotic.”

After deliberation, the jury convicted Grimshaw of felony sexual intercourse without

consent. The District Court sentenced him to 40 years at the Montana State Prison with 20

years suspended. Grimshaw appeals.

STANDARD OF REVIEW

¶17 We review a district court’s ruling on the admissibility of expert testimony for an

abuse of discretion. State v. St. Germain, 2007 MT 28, ¶ 14, 336 Mont. 17, 153 P.3d 591

(citations omitted). An abuse of discretion occurs when a district court acts arbitrarily or

unreasonably, resulting in substantial injustice. State v. Holland, 2019 MT 128, ¶ 8, 396

Mont. 94, 443 P.3d 519 (citing State v. Zimmerman, 2018 MT 94, ¶ 13, 391 Mont. 210,

417 P.3d 289). “Although a district court possesses broad discretion to determine the

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admissibility of evidence, judicial discretion must be guided by the Rules of Evidence,

applicable statutes, and principles of law.” Zimmerman, ¶ 13 (citing Maier v. Wilson, 2017

MT 316, ¶ 17, 390 Mont. 43, 409 P.3d 878).

DISCUSSION

¶18 Whether the District Court abused its discretion and compromised Grimshaw’s

right to a fair trial by allowing expert testimony regarding statistics about false

reports of sexual assault.

¶19 On appeal, Grimshaw argues the expert testimony regarding the statistics around

false reports of rape prejudiced his right to a fair trial by turning the case into a “trial by

statistic,” rather than one based on the specific facts of this case. The State argues the

District Court, granted broad discretion to admit relevant expert witness testimony, did not

abuse its discretion by admitting the statistical testimony. The State further argues that,

even if the admission of such testimony was an abuse of discretion, its admission was

ultimately harmless due to the significant admissible evidence that T.G. did not consent to

sex with Grimshaw.

¶20 We begin by first analyzing whether the admission of the expert witness testimony

as it relates to statistical rates of false reports of sexual assault was an abuse of discretion.

We will find a district court to have abused its discretion when it “acts arbitrarily or

unreasonably, resulting in substantial injustice.” Holland, ¶ 8.

¶21 “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.” M. R. Evid. 702. “It is well settled in Montana that the

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determination of the credibility of witnesses and the weight to be given their testimony is

solely within the province of the jury.” Brodniak, 221 Mont. at 222, 718 P.2d at 329

(citations omitted). “An expert witness may not comment on the credibility of the victim’s

testimony.” Rogers v. State, 2011 MT 105, ¶ 26, 360 Mont. 334, 253 P.3d 889 (citing St.

Germain, ¶ 27).

¶22 The State presented the testimony of Dr. Vanino as a “blind expert” who would

testify to rape myths and the behaviors of victims. For much of her testimony, this is what

she did. Eventually, however, the State asked Dr. Vanino to get into the false reporting

statistics. Dr. Vanino testified the statistics show between two and eight percent of sexual

assault reports are false.

¶23 In Brodniak, we reviewed the testimony of a psychologist, called as an expert

witness, who had examined the victim of a sexual assault to determine if she had symptoms

consistent with rape trauma syndrome. During his testimony, the psychologist testified to

both the statistical percentage of false rape allegations and to his opinion as to whether the

victim was malingering. Brodniak, 221 Mont. at 219-222, 718 P.2d at 327-29. We held

the psychologist’s testimony “with regard to malingering and the statistical percentage of

false accusations was improper comment on the credibility of” the witness. Brodniak, 221

Mont. at 222, 718 P.2d at 329.

¶24 While Dr. Vanino was testifying as a blind expert about rape myths and symptoms

or behaviors common to victims of sexual assault and had not personally examined T.G.,

unlike the psychologist in Brodniak, we reach the same conclusion about her testimony

regarding the statistics of false sexual assault reports as we did in that case. Presenting

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testimony that only between two and eight percent of sexual assault reports are false clearly

commented on, and improperly bolstered, the credibility of T.G.’s testimony. The clear

inference of the statistical testimony in this case was that there is a 92-98% probability that

Grimshaw was guilty of the charged offense such that T.G. was telling the truth as

compared to a 2-8% probability T.G. had made a false accusation.

¶25 The State argues Dr. Vanino’s testimony was similar to expert witness testimony on

battered woman syndrome, which we noted “assists the jury in understanding the woman’s

actions” in State v. Walker, 2018 MT 312, ¶ 42, 394 Mont. 1, 433 P.3d 202 (emphasis

added). Much of Dr. Vanino’s testimony was indeed similar to this type of testimony—

such as her testimony regarding common misconceptions surrounding rape and victim

behavior. The statistical probability testimony at issue here, however, is not at all similar

to expert testimony on battered woman syndrome and typical symptoms or behaviors

exhibited by those suffering from the syndrome. Dr. Vanino testified that only between

two and eight percent of sexual assault reports are false. This testimony, in essence,

vouched for T.G.’s credibility in a case where T.G. claims she was sexually assaulted and

Grimshaw claims her report is false. See Walker, ¶ 46. Such credibility-boosting expert

testimony is improper.

¶26 The State further alleges Grimshaw was the one who opened the door to the

introduction of statistical evidence by contending T.G. falsely accused him of rape and the

State had a right to rebut this defense. “When one party opens the door, or broaches a

certain topic that would otherwise be off limits, ‘the opposing party has the right to offer

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evidence in rebuttal . . . .’” State v. Guill, 2010 MT 69, ¶ 39, 355 Mont. 490, 228 P.3d

1152 (quoting State v. Veis, 1998 MT 162, ¶ 18, 289 Mont. 450, 962 P.2d 1153).

¶27 While the State certainly has a right to rebut a defendant’s chosen defense, a

defendant alleging he is innocent of a sexual crime does not open the door for the State to

present statistical evidence that shows a defendant is between 92 and 98% likely to be

guilty simply by virtue of being accused. Such an interpretation would turn the

presumption of innocence on its head for all sexual crimes. Further, it was the State who

elicited the statistical data from Dr. Vanino—not Grimshaw. On cross-examination,

Dr. Vanino responded to one of Grimshaw’s counsel’s questions by saying she was “happy

to talk to you about the false reporting statistics if I’m allowed to get into that because that

sounds like what you’re asking about.” Grimshaw’s counsel moved on and did not get into

the false reporting statistics. On rebuttal, the State pounced on defense counsel’s avoidance

of the false reporting statistics, commenting Grimshaw “didn’t really want to get into”

these statistics—insinuating Grimshaw was attempting to hide evidence from the jury—

and then directly asked Dr. Vanino “what are those false reporting statistics?” It was only

then that Dr. Vanino testified to the two to eight percent false reporting statistic.

Grimshaw’s questioning did not open the door for the State to present this improper

statistical evidence. This evidence was not put on to inform the jury on symptoms or

behaviors of sexual assault victims to better understand T.G.’s behaviors, but rather for the

sole purpose of bolstering T.G.’s credibility.

¶28 Because we find Dr. Vanino’s testimony about the rate of false reports of sexual

assault was improper and Grimshaw did not open the door to such testimony, we hold the

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District Court abused its discretion in admitting such testimony. The District Court, which

had admittedly not read Brodniak when it ruled on Grimshaw’s objection, ignored the

mandates of Brodniak when it admitted Dr. Vanino’s testimony regarding statistics. The

District Court acted arbitrarily and unreasonably by admitting Dr. Vanino’s testimony over

Grimshaw’s objection. Holland, ¶ 8.

¶29 Finding the District Court abused its discretion in admitting the statistical testimony,

we now turn to whether Grimshaw’s right to a fair trial was violated. Because the error in

this case was the improper admission of evidence, it was “trial error.” State v. Van Kirk,

2001 MT 184, ¶ 40, 306 Mont. 215, 32 P.3d 735. Trial error is neither presumptively

prejudicial nor automatically reversible. Van Kirk, ¶ 40. As we noted in Brodniak, we

“will not reverse a judgment of conviction for harmless error, and the question as to

whether a particular error is harmful or harmless depends on the facts of the case under

review.” Brodniak, 221 Mont. at 222-23, 718 P.2d at 329 (citing State v. Straight, 136

Mont. 255, 265, 347 P.2d 482, 488 (1959)). In order to prove trial error was harmless, the

State “must demonstrate that there is no reasonable possibility that the inadmissible

evidence might have contributed to the conviction.” Van Kirk, ¶ 47.

¶30 The State argues the statistical testimony, even if its admission was an abuse of

discretion, was merely harmless trial error because it presented admissible evidence T.G.

did not consent to sex with Grimshaw. It points to Grimshaw’s interview with police,

where he stated his encounter with T.G. “might have been a little, kind of, rape deal” and

told them he “did something that she didn’t want, and [he] did it forcibly” to support its

argument the jury was going to convict Grimshaw regardless of the statistical evidence

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presented. As both parties agree they had sex, the only issue at trial was whether T.G.

consented.

¶31 At trial, T.G. testified she did not consent. Grimshaw argued she did consent, and

falsely accused him of rape because she was ashamed of having sex with her cousin.

Grimshaw argued his statements to police in the recorded interview were essentially that

of a confused man attempting to explain having sex with his cousin to the police. The jury

was presented with the conflicting stories of both T.G. and Grimshaw and tasked with

making a determination of who was telling the truth about what happened in the early

morning hours of November 11, 2016.

¶32 The admission of the statistical evidence boosted T.G.’s credibility and ultimately

tipped the scales to an unfair trial. While there was admissible evidence tending to prove

Grimshaw’s guilt, such evidence was not so strong there was “no reasonable possibility”

the false reporting statistics could have contributed to his conviction. Dr. Vanino testified

to a two to eight percent chance of a false report of a sexual assault. T.G. reported

Grimshaw sexually assaulted her, and according to the statistical testimony presented at

trial, it implied there is a 92-98% chance she was telling the truth about that sexual assault.

In a case which turns on which party the jury believes, such numbers are impossible to

ignore. Grimshaw is entitled to be tried on the merits of his own case, and the admission

of the false reporting statistical evidence undermines our confidence that is what happened

here. Accordingly, we hold Grimshaw’s right to a fair trial was violated by the improper

admission of the false reporting statistics.

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¶33 This is ultimately a “he said-she said” consent case which turns solely on the

credibility of the parties, one of the most difficult for our legal system to handle. In this

case, the State’s improper use of credibility-boosting statistical evidence compromised the

integrity of Grimshaw’s trial. Grimshaw is therefore entitled to a new trial.

The District Court abused its discretion when it allowed expert witness testimony

on statistics regarding false claims of rape. The District Court’s error violated Grimshaw’s

right to a fair trial and the proper remedy is a new trial.

¶35 Reversed and remanded for a new trial.