Even if you are arrested for DUI, you are still presumed innocent until proven guilty. There are a number of ways to make this presumption hold up in court. For example, the prosecutor often lacks evidence on the driving element of DUI. That’s especially common in collision cases. By the time officers arrive on the scene, the defendant has exited the vehicle. So, it might be hard to prove, beyond a reasonable doubt that the defendant was driving.
But in most cases, intoxication, or the lack thereof, is the only real issue. The test compliance rate varies by jurisdiction. But generally, about 80 percent of drivers provide a breath or blood sample.