Virginia’s highest court has heard arguments about whether to overturn the conviction of a Fairfax County sex offender who was apprehended after police used a GPS to monitor his movements without obtaining a search warrant.

David L. Foltz was convicted of abduction with intent to defile in 2008. The Virginia Court of Appeals has upheld that conviction twice, saying police didn’t violate Foltz’s privacy rights by putting a GPS on his car while officers were investigating him in a series of sexual assaults.