2023 Wisconsin Statutes & Annotations › Chapter 907 - Evidence — opinions and expert testimony. › 907.02 - Testimony by experts.

907.02
Testimony by experts.
(1)
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 the testimony is based upon sufficient facts or data, the testimony is the product of reliable principles and methods, and the witness has applied the principles and methods reliably to the facts of the case.
(2)
Notwithstanding sub. (1), the testimony of an expert witness may not be admitted if the expert witness is entitled to receive any compensation contingent on the outcome of any claim or case with respect to which the testimony is being offered.
History:  Sup. Ct. Order, 59 Wis. 2d R1, R206 (1973); 2011 a. 2.
A chemist testifying as to the alcohol content of blood may not testify as to the physiological effect that the alcohol would have on the defendant. State v. Bailey, 54 Wis. 2d 679, 196 N.W.2d 664 (1972).
The trial court abused its discretion in ordering the defendant to make its expert available for adverse examination because the agreement was for the exchange of expert reports only and did not include adverse examination of the expert retained by the defendant. Blakely v. Waukesha Foundry Co., 65 Wis. 2d 468, 222 N.W.2d 920 (1974).
In a personal injury action, the court did not err in permitting a psychologist specializing in behavioral disorders to refute a physician's medical diagnosis when the specialist was a qualified expert. Qualification of an expert is a matter of experience, not licensure. Karl v. Employers Insurance of Wausau, 78 Wis. 2d 284, 254 N.W.2d 255 (1977).
The standard of nonmedical, administrative, ministerial, or routine care in a hospital need not be established by expert testimony. Any claim against a hospital based on negligent lack of supervision requires expert testimony. Payne v. Milwaukee Sanitarium Foundation, Inc., 81 Wis. 2d 264, 260 N.W.2d 386 (1977).
In the absence of some additional expert testimony to support the loss, a jury may not infer permanent loss of earning capacity from evidence of permanent injury. Koele v. Radue, 81 Wis. 2d 583, 260 N.W.2d 766 (1978).
A res ipsa loquitur instruction permits a jury to draw an inference of general negligence from the circumstantial evidence. Before a res ipsa loquitur instruction can be given, the evidence must conform to these requirements: 1) the event in question must be of the kind that does not ordinarily occur in the absence of negligence; and 2) the agency or instrumentality causing the harm must have been within the exclusive control of the defendant. A res ipsa loquitur instruction may be grounded on expert testimony in a medical malpractice case; the res ipsa loquitur standards are satisfied if the testimony and the medical records taken as a whole would support the inference of negligence or if direct testimony is introduced that the injury in question was of the nature that does not ordinarily occur if proper skill and care are exercised. Kelly v. Hartford Casualty Insurance Co., 86 Wis. 2d 129, 271 N.W.2d 676 (1978).
A hypothetical question may be based on facts not yet in evidence. Novitzke v. State, 92 Wis. 2d 302, 284 N.W.2d 904 (1979).
It was not error to allow psychiatric testimony regarding factors that could influence eye witness identification, but to not allow testimony regrading the application of those factors to the facts of the case. Hampton v. State, 92 Wis. 2d 450, 285 N.W.2d 868 (1979).
A psychiatric witness, whose qualifications as an expert were conceded, had no scientific knowledge on which to base an opinion as to the accused's lack of specific intent to kill. State v. Dalton, 98 Wis. 2d 725, 298 N.W.2d 398 (Ct. App. 1980).
Medical records as explained to the jury by a medical student were sufficient to support a conviction; the confrontation right was not denied. Hagenkord v. State, 100 Wis. 2d 452, 302 N.W.2d 421 (1981).
Polygraph evidence is inadmissible in any criminal proceeding. State v. Dean, 103 Wis. 2d 228, 307 N.W.2d 628 (1981).
Stating guidelines for admission of testimony by hypnotized witnesses. State v. Armstrong, 110 Wis. 2d 555, 329 N.W.2d 386 (1983).
No witness, expert or otherwise, should be permitted to give an opinion that another mentally and physically competent witness is telling the truth. State v. Haseltine, 120 Wis. 2d 92, 352 N.W.2d 673 (Ct. App. 1984).
Expert testimony regarding fingernail comparisons for identification purposes was admissible. State v. Shaw, 124 Wis. 2d 363, 369 N.W.2d 772 (Ct. App. 1985).
Bite mark evidence presented by experts in forensic odontology was admissible. State v. Stinson, 134 Wis. 2d 224, 397 N.W.2d 136 (Ct. App. 1986).
An expert may give opinion testimony regarding the consistency of the complainant's behavior with that of victims of the same type of crime only if the testimony will assist the fact-finder in understanding evidence or determining a fact, but the expert is prohibited from testifying about the complainant's truthfulness. State v. Jensen, 147 Wis. 2d 240, 432 N.W.2d 913 (1988).
Experience, as well as technical and academic training, is the proper basis for giving expert opinion. State v. Hollingsworth, 160 Wis. 2d 883, 467 N.W.2d 555 (Ct. App. 1991).
If the state seeks to introduce testimony of experts who have personally examined a sexual assault victim that the victim's behavior is consistent with other victims, a defendant may request an examination of the victim by its own expert. State v. Maday, 179 Wis. 2d 346, 507 N.W.2d 365 (Ct. App. 1993). See also State v. Schaller, 199 Wis. 2d 23, 544 N.W.2d 247 (Ct. App. 1995), 94-1216.
Expert opinion regarding victim recantation in domestic abuse cases is permissible. State v. Bednarz, 179 Wis. 2d 460, 507 N.W.2d 168 (Ct. App. 1993).
When the state inferred that a complainant sought psychological treatment as the result of a sexual assault by the defendant, but did not offer the psychological records or opinions of the therapist as evidence, it was not improper for the court to deny the defendant access to the records after determining that the records contained nothing material to the fairness of the trial. State v. Mainiero, 189 Wis. 2d 80, 525 N.W.2d 304 (Ct. App. 1994).
An expert may give an opinion about whether a person's behavior and characteristics are consistent with battered woman's syndrome, but may not give an opinion on whether the person had a reasonable belief of being in danger at the time of a particular incident. State v. Richardson, 189 Wis. 2d 418, 525 N.W.2d 378 (Ct. App. 1994).
Expert testimony is necessary to establish the point of impact of an automobile accident. Wester v. Bruggink, 190 Wis. 2d 308, 527 N.W.2d 373 (Ct. App. 1994).
Scientific evidence is admissible, regardless of underlying scientific principles, if it is relevant, the witness is qualified as an expert, and the evidence will assist the trier of fact. State v. Peters, 192 Wis. 2d 674, 534 N.W.2d 867 (Ct. App. 1995).
An indigent may be entitled to have the court compel the attendance of an expert witness. It may be error to deny a request for an expert to testify on the issue of suggestive interview techniques used with a young child witness if there is a “particularized need" for the expert. State v. Kirschbaum, 195 Wis. 2d 11, 535 N.W.2d 462 (Ct. App. 1995), 94-0899.
Items related to drug dealing, including gang-related items, is a subject of specialized knowledge and a proper topic for testimony by qualified narcotics officers. State v. Brewer, 195 Wis. 2d 295, 536 N.W.2d 406 (Ct. App. 1995), 94-1477.
Generally expert evidence of personality dysfunction is irrelevant to the issue of intent in a criminal trial, although it might be admissible in very limited circumstances. State v. Morgan, 195 Wis. 2d 388, 536 N.W.2d 425 (Ct. App. 1995), 93-2611.
As with still photographers, a video photographer's testimony that a videotape accurately portrays what the photographer saw is sufficient foundation for admission of the videotape, and expert testimony is not required. State v. Peterson, 222 Wis. 2d 449, 588 N.W.2d 84 (Ct. App. 1998), 97-3737.
It was error to exclude as irrelevant a psychologist's testimony that the defendant did not show any evidence of having a sexual disorder and that absent a sexual disorder a person is unlikely to molest a child because the psychologist could not say that the absence of a sexual disorder made it impossible for the defendant to have committed the alleged act. State v. Richard A.P., 223 Wis. 2d 777, 589 N.W.2d 674 (Ct. App. 1998), 97-2737. See also State v. Davis, 2002 WI 75, 254 Wis. 2d 1, 645 N.W.2d 913, 00-2916.
When the issue is whether expert testimony may be admitted, and not whether it is required, a court should normally receive the expert testimony if the requisite conditions have been met and the testimony will assist the trier of fact. State v. Watson, 227 Wis. 2d 167, 595 N.W.2d 403 (1999), 95-1067.
A witness's own testimony may limit the witness's qualifications. A witness who disavowed being qualified to testify regarding the safety of a product was disqualified to testify as an expert on the product's safety. Green v. Smith & Nephew AHP, Inc., 2001 WI 109, 245 Wis. 2d 772, 629 N.W.2d 727, 98-2162.
If the state is to introduce Jensen, 147 Wis. 2d 240 (1988), evidence through a psychological expert who has become familiar with the complainant through ongoing treatment, or through an intensive interview or examination focused on the alleged sexual assault, the defendant must have the opportunity to show a need to meet that evidence through a psychological expert of its own as required by  Maday, 179 Wis. 2d 346 (1993). State v. Rizzo, 2002 WI 20, 250 Wis. 2d 407, 640 N.W.2d 93, 99-3266.
A determination of whether the state “retains" an expert for purposes of Maday, 179 Wis. 2d 346 (1993), cannot stand or fall on whether or how it has compensated its expert. An expert's status as the complainant's treating therapist does not preclude that expert from being “retained" by the state for purposes of Maday. State v. Rizzo, 2002 WI 20, 250 Wis. 2d 407, 640 N.W.2d 93, 99-3266.
When an expert was permitted to testify in a sexual assault case about common characteristics of sexual assault victims and the consistency of those characteristics with those of the victim at trial, a standing objection to the expert's testifying was insufficient to preserve specific errors resulting from the testimony. State v. Delgado, 2002 WI App 38, 250 Wis. 2d 689, 641 N.W.2d 490, 01-0347.
For a defendant to establish a constitutional right to the admissibility of proffered expert testimony, the defendant must satisfy a two-part inquiry determining whether the evidence is clearly central to the defense and the exclusion of the evidence is arbitrary and disproportionate to the purpose of the rule of exclusion, so that exclusion undermines fundamental elements of the defendant's defense. State v. St. George, 2002 WI 50, 252 Wis. 2d 499, 643 N.W.2d 777, 00-2830.
Under the first part of the inquiry, a defendant must demonstrate that the proffered testimony satisfies each of the following four requirements: 1) the testimony of the expert witness meets the standards under this section governing the admission of expert testimony; 2) the expert testimony is clearly relevant to a material issue in the case; 3) the expert testimony is necessary to the defendant's case; and 4) the probative value of the expert testimony outweighs its prejudicial effect. Under the second part of the inquiry, the court must determine whether the defendant's right to present the proffered evidence is nonetheless outweighed by the state's compelling interest to exclude the evidence. State v. St. George, 2002 WI 50, 252 Wis. 2d 499, 643 N.W.2d 777, 00-2830.
An expert's specious claims about his credentials did not render his testimony incredible or render him unqualified as a matter of law. To hold testimony incredible requires that the expert's testimony be in conflict with the uniform course of nature or with fully established or conceded facts. Questions of reliability are left for the trier of fact. Ricco v. Riva, 2003 WI App 182, 266 Wis. 2d 696, 669 N.W.2d 193, 02-2621.
Field sobriety tests are not scientific tests. They are merely observational tools that law enforcement officers commonly use to assist them in discerning various indicia of intoxication, the perception of which is necessarily subjective. The procedures an officer employs in determining probable cause for intoxication go to the weight of the evidence, not its admissibility. City of West Bend v. Wilkens, 2005 WI App 36, 278 Wis. 2d 643, 693 N.W.2d 324, 04-1871.
The U.S. Supreme Court and Wisconsin Supreme Court have recognized that, although it is not easy to predict future behavior and psychiatrists and psychologists are not infallible, they can opine about future behavior. Brown County v. Shannon R., 2005 WI 160, 286 Wis. 2d 278, 706 N.W.2d 269, 04-1305.
The fact that the witness was a forensic scientist did not preclude her from forming an expert opinion about the accuracy of a desk reference based on experience. The forensic scientist properly used the Physician's Desk Reference to presumptively determine the identity of suspected Oxycontin. The result of this presumptive test was supported both by a confirmatory test and other circumstantial evidence. State v. Stank, 2005 WI App 236, 288 Wis. 2d 414, 708 N.W.2d 43, 04-1162.
There is no presumption of the admissibility of expert eyewitness testimony in cases involving eyewitness identification. State v. Shomberg, 2006 WI 9, 288 Wis. 2d 1, 709 N.W.2d 370, 04-0630.
No expert should be permitted to give an opinion that another mentally and physically competent witness is telling the truth. An opinion that a complainant was sexually assaulted or is telling the truth is impermissible. In asserting that because the complainant was not highly sophisticated she would not have been able to maintain consistency throughout her interview unless it was something that she experienced, a witness testified that the complainant had to have experienced the alleged contact with defendant. The testimony was tantamount to an opinion that the complainant was telling the truth. State v. Krueger, 2008 WI App 162, 314 Wis. 2d 605, 762 N.W.2d 114, 07-2064.
Expert testimony must assist the trier of fact to understand the evidence or to determine a fact in issue. A suggested test for deciding when experts may be used is whether the untrained layperson would be qualified to determine intelligently and to the best possible degree the particular issue without enlightenment from those having a specialized understanding of the subject. The proper standard is helpfulness, not absolute necessity. State v. Swope, 2008 WI App 175, 315 Wis. 2d 120, 762 N.W.2d 725, 07-1785.
Whether a witness is qualified to give an opinion depends upon whether the witness has superior knowledge in the area in which the precise question lies. State v. Swope, 2008 WI App 175, 315 Wis. 2d 120, 762 N.W.2d 725, 07-1785.
Expert testimony is not generally required to prove a party's negligence, and requiring expert testimony before a claim can get to the jury is an extraordinary step that should be ordered only when unusually complex or esoteric issues are before the jury. This principal applies equally to a breach of contract action because it is a general rule that expert testimony is not necessary when the issue is within the realm of the ordinary experience of the average juror. Racine County v. Oracular Milwaukee, Inc., 2009 WI App 58, 317 Wis. 2d 790, 767 N.W.2d 280, 07-2861.
Affirmed. 2010 WI 25, 323 Wis. 2d 682, 781 N.W.2d 88, 07-2861.
In an operating while intoxicated (OWI) prosecution, even if a defendant establishes a constitutional right to present an expert opinion that is based in part on portable breath test results, applying the St. George, 2002 WI 50, test, the right to do so is outweighed by the state's compelling interest to exclude that evidence. Permitting the use of that evidence as the basis for an expert opinion would render meaningless the legislature's forbidding of that evidence in OWI prosecutions under s. 343.303, an act that promotes efficient investigations of suspected drunk driving incidents and furthers the state's compelling interest in public safety on its roads. State v. Fischer, 2010 WI 6, 322 Wis. 2d 265, 778 N.W.2d 629, 07-1898.
An electronic monitoring device (EMD) report did not present an issue that is particularly complex or unusually esoteric. Additionally, the EMD involves scientific principles that are indisputable and fully within the lay comprehension of the average juror. As such, expert testimony was not required to properly establish a foundation for the report's admissibility. State v. Kandutsch, 2011 WI 78, 336 Wis. 2d 478, 799 N.W.2d 865, 09-1351.
The Admissibility of Novel Scientific Evidence: The Current State of the Frye Test in Wisconsin. Van Domelen. 69 MLR 116 (1985).
Scientific Evidence in Wisconsin: Using Reliability to Regulate Expert Testimony. Kubiak. 74 MLR 261 (1991).
State v. Dean: A Compulsory Process Analysis of the Inadmissibility of Polygraph Evidence. Katz. 1984 WLR 237.
The Psychologist as an Expert Witness. Gaines. WBB Apr. 1973.
Scientific Evidence in Wisconsin after Daubert. Blinka. Wis. Law. Nov. 1993.
The Use and Abuse of Expert Witnesses. Brennan. Wis. Law. Oct. 1997.
NOTE:  The above annotations relate to this section as it existed prior to 2011 Wis. Act 2, which added a new standard to sub. (1) and created sub. (2).
Expert testimony about retrograde extrapolation of the defendant's blood alcohol concentration was admissible. The court's gate-keeper function is to ensure that the expert's opinion is based on a reliable foundation and is relevant to material issues. The court is to focus on the principles and methodology the expert relies upon, not on the conclusion generated. The question is whether the scientific principles and methods that the expert relies upon have a reliable foundation in the knowledge and experience of the expert's discipline. State v. Giese, 2014 WI App 92, 356 Wis. 2d 796, 854 N.W.2d 687, 13-2009.
If experts are in disagreement, it is not for the court to decide which of several competing scientific theories has the best provenance. The accuracy of the facts upon which the expert relies and the ultimate determinations of credibility and accuracy are for the jury, not the court. As stated in Daubert, 509 U.S. 579 (1993), vigorous cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof are the traditional and appropriate means of attacking shaky but admissible evidence. State v. Giese, 2014 WI App 92, 356 Wis. 2d 796, 854 N.W.2d 687, 13-2009.
The evidentiary standard under sub. (1) made effective February 1, 2011, did not apply to expert testimony in the ch. 980 discharge petition trials in this case because the discharge petitions did not “commence" “actions" or “special proceedings" but were part of the underlying commitments. The original ch. 980 commitments in this case began several years before the standard was adopted, and the filings in this case did not constitute the “commencement" of an “action" or a “special proceeding." Because the legislature had a rational basis for not applying the evidentiary standards under sub. (1) to expert testimony in post-February 1, 2011, discharge petitions that seek relief from pre-February 1, 2011, commitments, no violation of equal protection or due process occurred. State v. Alger, 2015 WI 3, 360 Wis. 2d 193, 858 N.W.2d 346, 13-0225.
Sub. (1) adopts the reliability test established by Daubert, 509 U.S. 579 (1993).  Daubert itself acknowledges that its test for the admissibility of expert evidence is “flexible." In this case, the proposed expert testimony did not neatly fit the Daubert factors. This did not, however, require exclusion. The court appropriately considered other factors bearing upon the reliability of the testimony and found that she had “sufficient knowledge, skill, experience, and training" to qualify her as an expert. State v. Smith, 2016 WI App 8, 366 Wis. 2d 613, 874 N.W.2d 610, 14-2653.
The drug recognition evaluation (DRE) protocol is a nationally standardized protocol for identifying drug intoxication based on the well-established concept that drugs cause observable signs and symptoms, affecting vital signs and changing the physiology of the body, and testimony based on the DRE protocol is subject to sub. (1). State v. Chitwood, 2016 WI App 36, 369 Wis. 2d 132, 879 N.W.2d 786, 15-0097.
Daubert, 509 U.S. 579 (1993), provided the following illustrative, non-exhaustive list of factors a court may consider in deciding whether expert testimony based upon scientific, technical, or other specialized knowledge is reliable: 1) whether the theory or technique employed by the expert is generally accepted in the relevant community; 2) whether it has been subject to peer review and publication; 3) whether it has been tested; and 4) whether the known or potential rate of error is acceptable. State v. Chitwood, 2016 WI App 36, 369 Wis. 2d 132, 879 N.W.2d 786, 15-0097.
A trial court's obligation to act as a gatekeeper under Daubert, 509 U.S. 579 (1993), does not require it to conduct a Daubert admissibility analysis if there is no objection to the testimony, and the trial court's failure to sua sponte engage in such an analysis does not constitute plain error under s. 901.03 (4). State v. Cameron, 2016 WI App 54, 370 Wis. 2d 661, 885 N.W.2d 611, 15-1088.
To determine whether expert testimony is admissible under sub. (1), a court must engage in a three-step analysis, considering whether: 1) the witness is qualified; 2) the witness's methodology is scientifically reliable; and 3) the testimony will assist the trier of fact to determine a fact in issue. Bayer v. Dobbins, 2016 WI App 65, 371 Wis. 2d 428, 885 N.W.2d 173, 15-1470.
A trial court should admit medical expert testimony if physicians would accept it as useful and reliable. Expert medical opinion testimony is reliable if the knowledge underlying it has a reliable basis in the knowledge and experience of the relevant discipline. Instead of exclusion, the appropriate means of attacking shaky but admissible experience-based medical expert testimony is by vigorous cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof. Seifert v. Balink, 2017 WI 2, 372 Wis. 2d 525, 888 N.W.2d 816, 14-0195.
When the reliability of expert medical testimony is challenged under the reliability prong of sub. (1), the specific focus is on the reliability of the methods used by the expert. The trial court must be satisfied that the testimony is reliable by a preponderance of the evidence. In expert medical evidence, the methodology often relies on judgment based on the witness's knowledge and experience. Reliability concerns may focus on the personal knowledge and experience of the medical expert witness. A circuit court has discretion in determining the reliability of an expert's principles, methods, and the application of the principles and methods to the facts of the case. Seifert v. Balink, 2017 WI 2, 372 Wis. 2d 525, 888 N.W.2d 816, 14-0195.
Because the expert in question applied an accepted medical method relied upon by physicians and had extensive personal experiences and knowledge pertaining to the standard of reasonable care, the circuit court did not erroneously exercise its discretion in admitting the expert's testimony. Failure to rely on literature is no bar to admissibility. Daubert, 509 U.S. 579 (1993), supports the circuit court in the instant case: publication, which is but one element of peer review, is not a sine qua non of admissibility; it does not necessarily correlate with reliability. Seifert v. Balink, 2017 WI 2, 372 Wis. 2d 525, 888 N.W.2d 816, 14-0195.
A social worker's testimony about the absence of indications during a cognitive graphic interview of an alleged child sexual assault victim, either that the child had been coached or was being dishonest, did not violate the rule prohibiting a witness from giving an opinion that another mentally and physically competent witness is telling the truth, and was admissible for three reasons: 1) the testimony was limited to the social worker's observations of indications of coaching and dishonesty; 2) by limiting her testimony to indications of coaching and dishonesty, the social worker did not provide a subjective opinion as to the child's truthfulness; and 3) such testimony may assist the jury. State v. Maday, 2017 WI 28, 374 Wis. 2d 164, 892 N.W.2d 611, 15-0366.
The general principles of Daubert, 509 U.S. 579 (1993), are not limited to scientific knowledge. The analysis applies to all expert testimony. State v. Jones, 2018 WI 44, 381 Wis. 2d 284, 911 N.W.2d 97, 15-2665.
Sub. (1) requires that circuit courts make five determinations before admitting expert testimony: 1) whether the scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue; 2) whether the expert is qualified as an expert by knowledge, skill, experience, training, or education; 3) whether the testimony is based upon sufficient facts or data; 4) whether the testimony is the product of reliable principles and methods; and 5) whether the witness has applied the principles and methods reliably to the facts of the case. State v. Jones, 2018 WI 44, 381 Wis. 2d 284, 911 N.W.2d 97, 15-2665.
The admissibility of expert testimony is governed by this section. The court's role with regard to the admissibility of evidence is often described as that of a gatekeeper. Before 2011 Wis. Act 2, the court's role was simply to determine whether the evidence made a fact of consequence more or less probable. The heightened standard under this amended section does not change this gatekeeping function. It does, however, require more of the gatekeeper. Instead of simply determining whether the evidence makes a fact of consequence more or less probable, courts must now also make a threshold determination as to whether the evidence is reliable enough to go to the factfinder. State v. Jones, 2018 WI 44, 381 Wis. 2d 284, 911 N.W.2d 97, 15-2665.
Expert testimony at a Machner, 92 Wis. 2d 797 (1979), hearing regarding the reasonableness of trial counsel's performance is admissible, but only to the extent the expert focuses on factual matters and does not offer the expert's opinion on the reasonableness of trial counsel's conduct or strategy. Expert testimony is admissible to address questions of fact, not law. State v. Pico, 2018 WI 66, 382 Wis. 2d 273, 914 N.W.2d 95, 15-1799.
Sub. (1) continues to permit an expert witness to testify in the form of an opinion “or otherwise,” including exposition testimony on general principles without explicitly applying those principles to, or even having knowledge of, the specific facts in the case. If an expert testifies in the form of an opinion, then the expert must apply the principles and methods reliably to the facts of the case. State v. Dobbs, 2020 WI 64, 392 Wis. 2d 505, 945 N.W.2d 609, 18-0319.
When expert testimony is proffered in the form of an exposition on general principles, the circuit court, as gatekeeper, must consider the following four factors: 1) whether the expert is qualified; 2) whether the testimony will address a subject matter on which the factfinder can be assisted by an expert; 3) whether the testimony is reliable; and 4) whether the testimony will fit the facts of the case. State v. Dobbs, 2020 WI 64, 392 Wis. 2d 505, 945 N.W.2d 609, 18-0319.
There is no categorical rule that would condition the admissibility of relevant canine scent evidence on there being physical or forensic evidence corroborating the dog alerts. Rather, expert testimony regarding dog alerts, like all other expert testimony, may be admitted if the court concludes the evidence satisfies the threshold reliability criteria in this section and is not otherwise subject to exclusion under s. 904.03. State v. Bucki, 2020 WI App 43, 393 Wis. 2d 434, 947 N.W.2d 152, 18-0999.
Sub. (1) requires the trial court to determine, by a preponderance of the evidence and according to whichever criteria it deems appropriate, that the proffered expert testimony is based on adequate facts and a sound methodology and is thus sufficiently reliable to go before a jury. Personal knowledge and experience may form the basis for expert testimony. In certain fields, experience is the predominant, if not sole, basis for a great deal of reliable expert testimony. To assess reliability in this context, the witness must explain how the experience leads to the conclusion reached, why that experience is a sufficient basis for the opinion, and how that experience is reliably applied to the facts. State v. Hogan, 2021 WI App 24, 397 Wis. 2d 171, 959 N.W.2d 658, 19-2350.
Given the widespread availability of Fitbits and other similar wireless step-counting devices in today's consumer marketplace, the circuit court in this case reasonably concluded Fitbit evidence was not so unusually complex or esoteric that the jury needed an expert to understand it. State v. Burch, 2021 WI 68, 398 Wis. 2d 1, 961 N.W.2d 314, 19-1404.
The Daubert Standard in Wisconsin: A Primer. Blinka. Wis. Law. Mar. 2011.
Guarding the Gate: Six Years of Daubert in Wisconsin Courts. Aprahamian. Wis. Law. Mar. 2017.