Digital surveillance or objective evidence? Wearable-derived data in insurance and legal medicine: A narrative review and medico-legal perspective

Background: Wearable devices increasingly generate longitudinal data on physical activity, sleep, heart rate, falls, and other behavioral or physiological parameters. In insurance and legal medicine, these data may appear attractive as real-world evidence of functional capacity, disability, recovery, rehabilitation adherence, claimant behavior, or legally relevant factual circumstances. Their apparent objectivity, however, raises complex medico-legal questions. Objective: This narrative review examines the potential evidentiary value and medico-legal limitations of wearable-derived data in insurance and legal medicine, with particular attention to reliability, interpretation, privacy, consent, proportionality, transparency, and the risk of digital surveillance. Methods: A structured narrative review was conducted across PubMed/MEDLINE, Scopus, Google Scholar, and targeted legal, regulatory, technical, and grey-literature sources. Searches were conducted between March 2026 and May 2026, with a final update on 4 May 2026. Search terms combined concepts related to wearable devices, insurance medicine, disability evaluation, functional capacity, civil litigation, criminal proceedings, digital evidence, privacy, consent, and surveillance. Two authors independently screened sources for relevance, with disagreements resolved through discussion and, when needed, with the assistance of a third author. Results: The searches identified 276 records or sources. After removal of 68 duplicates, 208 records or sources were screened. Of these, 143 were excluded after title, abstract, or source-level screening. Sixty-five full-text sources were assessed for eligibility, and 40 sources were included in the final narrative synthesis. The included sources covered wearable-device validity and reliability, functional capacity and disability assessment, digital evidence and data provenance, insurance and legal evidentiary use, and privacy, consent, proportionality, and discrimination. Conclusion: Wearable-derived data may inform medico-legal reasoning, but they cannot by themselves establish disability, functional capacity, claimant credibility, or provide a self-sufficient reconstruction of legally relevant facts. A cautious, proportionate, and clinically contextualized approach is required before such data are used in insurance, civil, criminal, or broader legal medicine contexts.