David Hackbart is suing over his arrest in April of 2006 for disorderly conduct.
He flipped the bird at another driver, then made the gesture again when he heard someone yelling at him.
That second person was a police officer.
A judge later tossed out the charges, ruling that giving the finger is protected by the Constitution.
Jurors will now determine if Hackbart is entitled to damages for his arrest.
The American Civil Liberties Union contends city police officers aren't properly trained on free speech -- or finger -- issues.