A third judge has ruled that Iowa Department of Transportation officers issued speeding tickets for years without the legal authority to do so.

District associate judge Christine Dalton on Wednesday dismissed a ticket issued to Indianola attorney George Dunbar, who was cited for driving five miles over the speed limit along Interstate 80 near Davenport.

Dalton says that until lawmakers changed Iowa code earlier this year, DOT officers were "specifically restricted" for decades from stopping any noncommercial vehicles for traffic violations.

Two other judges have made similar rulings in the last year. Attorneys are considering seeking class-action relief for an estimated 20,000 drivers who have been nabbed for speeding by DOT officers.

Iowa lawmakers in May passed a law giving the DOT authority to issue traffic tickets for one year.