Taking a field sobriety test is one thing that police officers can ask drivers to do if they think a driver is drunk. The test, which is actually a battery of multiple tests, is supposed to clue the officer into whether the person is intoxicated. The issue here is that the tests aren't always accurate.
People in South Carolina are in a catch-22 position with field sobriety tests. You probably want to take the test so that you can show that you are sober; however, in doing so you run the risk of a false positive. That is a hard position to be placed in.