The jury deliberated about four hours Monday before finding police were not at fault in the death of 16-year-old Travone Bell.
The Charleston County Sheriff's Office, which operates the jail, was dropped as a defendant during the weeklong trial.
Authorities say Bell swallowed the drug when he was stopped for a traffic violation.
Attorney Michele Forsythe represented Bell's parents and said police should have done more to protect their son, who was too young to understand his mistake of swallowing crack cocaine.
Defense attorney Robin Jackson says police had no way of knowing Bell had swallowed crack because he denied it and was not showing symptoms.