In defending DUI cases, our Charleston DUI attorneys occasionally have clients who were told by law enforcement to “blow hard” into a breath test machine. We know that law enforcement may be telling people to “blow hard” because, under South Carolina law, the breath test operator must make a video recording of the entire breath test.
In South Carolina, the breath testing device is the DMT Datamaster. According to the DMT Datamaster’s Owner’s Manual, the “best breath sample is produced by a continuous exhalation. It does not need to be a hard blow . . . .” Essentially, the DMT Datamaster’s programming is designed to read from a “smooth exhalation,” not a hard burst of air. Further, the manual warns the operator – “Do not tell the subject to blow ‘hard'”.
We have defended numerous cases where the subject did not appear impaired on the video, but the machine still produced a blood-alcohol reading greater than the “legal limit.” All too often, our clients’ legal fate hangs on these machines’ readings, and it is important to have a Charleston DUI lawyer who can appropriately challenge whether the reading was accurate. If you are facing a DUI in Charleston, and you were told to “blow hard” while giving a breath test sample, then the court may exclude any evidence of your breath test because blowing hard might produce inaccurate test results.