An appeals court ruled Thursday that placing the device in a family vehicle does not constitute invasion of privacy.
Gloucester County Sheriff's Officer Kenneth Villanova sued private investigator Richard Leonard, who was hired by Villanova's now ex-wife in 2007.
The court says Leonard had recommended she buy the tracking device after her husband had thwarted efforts to tail him.
Leonard spotted Villanova leaving a driveway with a woman two weeks after the device was placed in a glove compartment.
The court said there was no evidence that the husband had driven the vehicle out of public view or to a private or secluded location where he could expect privacy.