South Carolina charges related to drugged driving are different compared to charges relating to driving under the influence of alcohol. In many drunk driving cases, authorities are able to pinpoint an individual's blood alcohol content as over the limit. However, in the case of drugged driving, there may not be any kind of test that can prove whether the driver had the drugs in his or her system or not while driving.
That said, verifiable proof that a substance was present in an individual's bloodstream is not always required to prove that he or she was guilty of drugged driving. Indeed, police might find evidence of illegal drugs or pharmaceuticals inside an accused person's vehicle. They might use that evidence along with evidence from failed field sobriety tests to convict the individual.