Law Enforcement Expert’s Testimony on Reasonable Suspicion Excluded
Posted on October 29, 2025 by Expert Witness Profiler
Plaintiff Shelby Ross asserted a Fourth Amendment unreasonable search and seizure claim against Defendant Jeremy Finney. In addition, Plaintiff asserted state law claims of assault and battery against Finney. Against Tipton County, Plaintiff averred “negligent failure to protect”/“negligent failure to prevent” claims under Tennessee law.
Ross hired Roy G. Taylor as an expert witness in areas such as police use-of-force policies, de-escalation techniques, and traffic stops.
Defendants argued that Taylor should be excluded as an expert because (1) his methods are not reliable under Daubert and (2) his report includes inadmissible legal conclusions about whether Finney had probable cause and reasonable suspicion to support his actions.
Law Enforcement Expert Witness
Roy Garvin Taylor is a former law enforcement officer and current adjunct professor with over forty years of experience “in various federal, state, local, and private Police Chief positions.” His areas of expertise include nationwide police procedures around traffic stops, use of force, and de-escalation techniques.
Discussion by the Court
I. Reliability
Defendants first argued that, under Daubert, Taylor “does not reliably employ principles and methods to base his conclusions.” Daubert’s factors ask “whether a method is testable, whether it has been subjected to peer review, the rate of error associated with the methodology, and whether the method is generally accepted within the scientific community.” Taylor’s opinions did not satisfy these factors, according to Defendants, because Taylor “generally relies upon his experience, education, and training in law enforcement.”
However, it is unclear what additional methodology Defendants would ask a police procedure expert to possess. After all, the methods of an expert in police procedure are not the kinds of methods that are regularly tested, peer reviewed, or accepted by the scientific community. As Ross pointed out, “Daubert is only of limited help in assessing technical or experiential expertise.”
Taylor’s qualifications include forty years of law enforcement and police training experience. Although his opinions fall outside the realm of science, the Court held that his personal knowledge and experience are appropriate substitutes to support a finding of reliability. Defendants will have a chance to challenge Taylor’s opinion through cross-examination and presentation of contrary evidence at trial, but exclusion is not the right path.
II. Inadmissible Legal Conclusions
Defendants next asserted that Taylor opined in his Initial Report about whether Finney had probable cause or reasonable suspicion to engage in certain actions on May 11, 2023. For her part, Ross conceded that some of the opinions in Taylor’s report “cross the line into ultimate questions of fact.”
Ross acknowledged that, to the extent Taylor used “phrases like ‘objectively unreasonable’ as a shorthand for something like ‘consistent with national standards,’ he should be required to use more precise language at trial.”
The Court concluded that Taylor cannot offer legal conclusions on questions including, but not limited to, reasonable suspicion, probable cause, whether conduct was lawful or unlawful, whether exigent circumstances existed, or whether a use of force constituted assault and battery. However, he may offer his opinions that do not include these terms and conclusions.
III. Supplemental Report
After Taylor submitted his initial report, and after he received the report of Defendants’ expert along with a copy of Tipton County’s police policies, Taylor submitted the supplemental report.
Defendants argued that, “at a minimum,” this supplemental report should be excluded because Taylor failed to include in his initial report “a complete statement of all opinions the witness will express and the basis and reasons for them.”
Instead, according to Defendants, Taylor later issued a supplemental report merely “as an attempt to bolster former opinions, provide totally new opinions, or combat the opinions of Defendants’ expert.”
Defendants further argued that Taylor’s analysis of the Tipton County police policies is irrelevant to this case, since there is no constitutional claim based on those policies nor any excessive force claim.
Because Taylor did not receive the police policies until after the Initial Report was written, Ross contended that he had a valid reason to supplement his earlier opinions. Ross further argued that the Tipton County use-of-force policies are still relevant to this case.
The Court deemed Taylor’s use-of-force analysis, drawn from the Tipton County police policies, relevant to this case, even though no Fourth Amendment excessive force claim is at issue, because the analysis of the state law assault and battery claim mirrors that of an excessive force claim.
Held
The Court granted in part and denied in part the Defendants’ motion to exclude the testimony of Plaintiff’s expert Roy Taylor.
Key Takeaway:
For nonscientific expertise such as Taylor’s, the relevant reliability concerns may focus on personal knowledge or experience. It helps that Taylor’s qualifications include forty years of law enforcement and police training
experience.
Case Details:
| Case Caption: | Ross V. Tipton County |
| Docket Number: | 2:24cv2313 |
| Court Name: | United States District Court, Tennessee Western |
| Order Date: | October 28, 2025 |
