With some exceptions (number of prior DUIs, serious physical injury, or death), a DUI is a misdemeanor in Alabama. The misdemeanor case is handled in Municipal or District Court. At that level, the trial is conducted by a Judge. District Court judges are elected and Municipal Judges are appointed by the local city council.
If a defendant prevails at the Municipal or District Court level then the case is concluded. However, if the Defendant loses at Municipal or District Court level then the Defendant can appeal de novo which is Latin for "from the beginning." The Defendant perfects an appeal to the Circuit Court by 1) filing a Notice of Appeal 2) perfecting an appeal bond. This must be done within 14 days of the date of disposition in District Court or Municipal Court.
Then the case is transferred to Circuit Court with the District or Municipal Court disposition eliminated like it never happened. One can also request a jury trial in Circuit Court. This often allows for the passage of time and the officer may loose some of the "vigor" towards the Defendant. Alternatively, a different prosecutor may handle the case. Occasionally, time does heal all.
The prosecution is prohibited from telling the jury that the defendant was convicted at the Municipal or District Court level. If a defendant loses a jury trial, then the case may be reviewed by an appellate court on legal issues.