State v. George Steven Burch, 2021 WI 68

On May 20, 2016 Nicole VanderHeyden was murdered; Brown County Sheriff investigators later matched DNA from the scene to George Burch and pursued leads.
In an unrelated June 2016 Green Bay Police Department (GBPD) investigation, Officer Bourdelais obtained Burch's written consent to search his Samsung cellphone; GBPD's forensic examiner performed a full physical extraction and stored the data in the department's long‑term records.
Two months later Sheriff’s Office detectives, after a DNA match, discovered the GBPD file (consent form + extracted phone data), reviewed the extracted data without a warrant, found Burch’s internet searches and a Gmail account, and obtained a warrant from Google for location data that placed Burch near key crime sites.
Burch moved to suppress the cellphone-derived evidence (arguing the download exceeded consent, retention was unlawful, and the Sheriff’s later access violated his Fourth Amendment privacy), and separately moved to exclude Fitbit step-count evidence tied to the victim’s boyfriend for lack of expert testimony and insufficient authentication.
The circuit court denied both motions (excluding only Fitbit sleep data); a jury convicted Burch of first‑degree intentional homicide; the Wisconsin Supreme Court affirmed the circuit court’s rulings.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Suppression of cellphone data (Fourth Amendment / exclusionary rule)	GBPD exceeded consent by extracting all data; retention was unlawful; Sheriff’s Office unlawfully accessed data later and should be barred by exclusion	State: GBPD obtained valid consent; Sheriff’s detectives reasonably relied on GBPD records and had no duty to get a new warrant; even if a violation occurred, exclusionary rule inapplicable because no culpable police misconduct	Denied suppression — even assuming a constitutional defect, exclusionary rule not warranted: detectives reasonably relied on documented consent and conduct was at most negligent, so no deterrence benefit to exclusion.
Fitbit evidence (expert testimony & authentication)	Fitbit step-counting requires expert proof of scientific reliability and proof that records were accurately transmitted and unmanipulated	State: Fitbits are common consumer devices; step-counting is within ordinary juror knowledge; Fitbit custodian affidavit and records suffice for authentication	Admissible — circuit court did not abuse discretion: expert testimony not required; records sufficiently authenticated as business records.

Herring v. United States, 555 U.S. 135 (2009) (exclusionary rule targets deliberate, reckless, or systemic police misconduct; isolated negligence does not justify suppression)
Davis v. United States, 564 U.S. 229 (2011) (exclusionary rule applied only after balancing deterrence benefits against social costs; good‑faith/reasonable reliance limits exclusion)
Riley v. California, 573 U.S. 373 (2014) (law enforcement generally must obtain a warrant before searching cell‑phone data)
Carpenter v. United States, 138 S. Ct. 2206 (2018) (historic location and digital data implicate heightened privacy expectations)
United States v. Leon, 468 U.S. 897 (1984) (good‑faith reliance on a warrant can preclude exclusion)
Arizona v. Evans, 514 U.S. 1 (1995) (reasonable reliance on computerized records maintained by third parties can negate deterrence rationale for exclusion)
United States v. Jones, 565 U.S. 400 (2012) (physical trespass and tracking of movements implicate Fourth Amendment protection of "effects")
State v. Kerr, 383 Wis. 2d 306 (2018) (applying federal exclusionary‑rule principles in Wisconsin: negligent or isolated mistakes do not merit suppression)