Part 2: Wearables on the Witness Stand

Contributed By:  Kris Carlson, COO, Former ICAC Commander, and Digital Forensics Investigator/Testifying Expert

Introduction: When Your Fitbit Becomes a Fact Witness

The line between personal health tech and courtroom evidence is fading. Smartwatches, fitness trackers, and medical IoT devices now monitor the steps, heart rates, sleep cycles, and even blood oxygen levels of millions of people. What was designed for wellness insights is increasingly surfacing in criminal investigations, civil disputes, and insurance claims.

In this second installment of Beyond the Screen, we examine the forensic value of wearable technology. From uncovering hidden timelines in criminal cases to shaping liability disputes in civil litigation, wearables are becoming digital witnesses. But with their evidentiary potential come serious challenges, chain-of-custody risks, privacy concerns, and governance gaps that courts, insurers, and employers must carefully navigate.

The Forensic Value of Wearables

Wearables generate continuous streams of biometric and contextual data, often timestamped and geo-tagged:

• Heart rate variability (HRV), stress indicators, and oxygen saturation
• GPS and motion activity (steps, exercise, sleep stages)
• Environmental inputs (temperature, elevation, noise exposure)
• Device metadata (sync logs, firmware updates, deletion records)

Unlike phone call logs or emails, these datasets are high-resolution and body-linked. They can provide investigators with minute-by-minute reconstructions of activity or inactivity that corroborate, or contradict, witness testimony [1].

Case Studies: Wearables in Court

1. Murder Timeline – Fitbit Data in Connecticut (State v. Dabate, 2019)
   Prosecutors used Fitbit logs showing the victim was still walking around an hour after her husband claimed she was killed. The discrepancy led to a conviction [7].
2. Disability Claim Fraud – Ohio Case (2016)
   A plaintiff seeking disability benefits claimed limited mobility, but Fitbit data showed sustained activity inconsistent with his testimony. The insurer successfully challenged the claim [7].
3. Workplace Injury Litigation – Canada (2015)
   Fitbit data was admitted in a personal injury case to demonstrate reduced activity levels after the accident, offering quantifiable proof of damages [7].
4. Domestic Violence Investigation – Pennsylvania (2018)
   Police used wearable data showing sudden spikes in heart rate and abrupt motion at the time of an assault, which helped corroborate testimony [7].

These cases demonstrate a trend: wearable data has tremendous value as it can be both incriminating and exculpatory, depending on whether it is considered as evidence in the first place (it should be!) and how it is collected, preserved, and contextualized.

Chain of Custody: Fragile Health-Linked Evidence

As with all digital evidence, wearable data must meet forensic soundness standards under the Federal Rules of Evidence 702 (expert testimony) and 901 (authentication), and withstand scrutiny under the Daubert Standard [1][2]. But wearables introduce unique risks:

• Sync Gaps – Devices store limited local data and sync only periodically. Missing synchronization data may create gaps in evidentiary timelines.
• User Control & Deletion – Like with many digital data sources, users can delete histories or reset devices.  Unless promptly preserved, data may be lost.
• Encryption & Proprietary Formats – Fitbit, Apple Health, and Garmin all use different APIs, encryption, and formats. Cross-device comparisons are problematic without standardized validation.
• Forensic Extraction Challenges – Tools like Cellebrite and Magnet AXIOM support partial extractions, but firmware and software result in collection issues and may jeopardize the ability to successfully preserve the device and could impact reproducibility.

Best practices, guided by ISO/IEC 27037 (evidence collection standards) and SWGDE best practices for IoT forensics, emphasize that wearables must be acquired through a controlled, validated, and logged process, not via ad hoc screenshots or app exports [3][4].

Privacy and Regulatory Risks

Wearable data straddles the line between personal health information (PHI) and general digital activity. That duality creates compliance conflicts:

• HIPAA – U.S. law treats health-related wearable data as PHI when handled by covered entities. Mishandling can trigger enforcement [5].
• GDPR (EU) – Classifies biometric and health data as “special categories,” requiring explicit consent and strict retention controls [6].
• Workplace Policies – Policies relating to wellness programs that may be tied to these devices might impact the ability to collect this data and may introduce liability to the employer if data is collected and used for something other than intended purpose.

Thus, wearable forensics is not just a technical issue!  Considerations with this data span legal, governance and ethics.

Implications for Key Stakeholders

For Insurers

• Wearable data can confirm or dispute disability, injury, or health-related claims.
• However, the selective or invalid use risks bad-faith litigation.

For Employers

• Aggregate wellness data must be walled off from HR decision-making.
• Improper use could invite EEOC enforcement or privacy litigation.

For Litigators

• Wearables can corroborate testimony, but only if the chain of custody and expert validation are airtight.
• Opposing counsel increasingly challenge wearable data as incomplete, biased, or manipulated [7].

The LCG Governance Playbook for Wearables

LCG recommends a wearable forensics readiness model:

1. Policy Clarity – Define acceptable use of wearable data in investigations and litigation.
2. Forensic Partnerships – Retain certified forensic experts with IoT and mobile experience [4].
3. Logging & Validation – Hash all exports, capture device state, and maintain chain-of-custody reports.
4. Privacy Safeguards – Apply HIPAA/GDPR principles: collect minimally, retain briefly, secure fully.
5. Litigation Strategy – Prepare experts to explain device error rates and limitations under Daubert review [2].

Looking Forward: Medical IoT and the Next Wave of Evidence

The evidentiary scope of wearable technology is expanding:

• Pacemakers and Insulin Pumps – Already cited in homicide and negligence cases.
• Continuous Glucose Monitors (CGMs) – Potentially relevant in healthcare compliance and malpractice litigation.
• Implantable IoT Devices – Raising unprecedented questions about privacy and admissibility.

As courts wrestle with data sourced “from inside the body,” governance frameworks and privacy issues will be tested as never before.

Final Thought: Fitness Trackers as Fact Finders

What began as lifestyle gadgets is now an evidentiary instrument. The stakes are high: insurers recalibrate their claims, employers reconsider their liability, and litigators rethink their strategy based on biometric breadcrumbs.

As with all digital forensics, the principle holds true: governance is not optional. Wearable evidence must be collected, preserved, and presented with the same rigor as any other form of electronic evidence. Otherwise, tomorrow’s Fitbit fact pattern risks collapsing under today’s legal scrutiny.

References

[1] Federal Rules of Evidence 702 (Expert Testimony) and 901 (Authentication). Cornell Law School LII.
[2] Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993) – Standard for admissibility of scientific and technical evidence.
[3] ISO/IEC 27037:2012 – Guidelines for identification, collection, acquisition, and preservation of digital evidence.
[4] Scientific Working Group on Digital Evidence (SWGDE) – Best Practices for Mobile and IoT Forensics.
[5] HIPAA Security Rule – U.S. Department of Health & Human Services.
[6] General Data Protection Regulation (GDPR), Articles 5 & 9 – Data minimization and protections for “special category” data.
[7] Case Law and Litigation Examples: State v. Dabate (CT Superior Court, 2019 – Fitbit homicide case); disability and injury litigation involving wearable evidence; Waymo v. Uber (2017 – spoliation & trade secrets).