I hope none of you ever have this problem, but if you ever get pulled over for a DUI you need to remember that you do not have to take the road side field sobriety test. This includes the horizontal gaze nystagmis test (follow the pen with your eyes) the walk and turn test and the one legged stand.
Your polite refusal to take these roadside gymnastics tests will not hurt your case. If you take the test the officer will likely say you failed and most sober people couldn't pass these tests anyway. You are required to take the breathalizer and should take it even if you have been drinking.
A refusal to take this test will result in a one year license revocation which is worse than a DUI. Just remember the more you say the harder your case is to defend.