There is no “legal limit” for driving under the influence in South Carolina because the State must prove that you were driving while appreciably and materially impaired, as opposed to what your blood alcohol level was at the time of the DUI arrest. Again, your blood alcohol content can prove impairment.
South Carolina DUI law provides for “deductions” based on the blood test or breathalyzer results, however:
If your blood alcohol content was 0.05 or less, it's assumed that you weren't under the influence of alcohol, although the prosecutor may also claim you were on drugs;
If your blood alcohol concentration was higher than 0.05 but lower than 0.08, there's no deduction whether you were intoxicated; and
If your blood alcohol level was 0.08 or more, the criminal court will tell the jury that they can presume that you were impaired, although you can still challenge the State’s evidence and present your evidence proving your sobriety.