One of the questions people sometimes have for criminal defense attorneys is whether or not one should submit to a chemical test when one is pulled over on suspicion of DUI. It is a good question, and it might be helpful to clarify the bases on which DUI charges can rest. From there, the question of refusing a test might be clarified.
There are various circumstances under which police can make an arrest for DUI, but two are quite common. The first is when an individual is suspected of compromising their ability to operate a motor vehicle safety due to alcohol intoxication. From the time officers first suspect an individual of driving under the influence, they gather as many observations as possible to support that conclusion, including all traffic violations and the appearance and demeanor of the driver. If enough of these observations pile up, police can gain probable cause to make an arrest, which can then support criminal charges.