Ontario courts can change or "amend up" a speeding ticket if the driver decides to fight it, the province's Court of Appeal ruled Thursday.

The ruling will affect cases in which police officers opt to cut speeding drivers a break by lowering their recorded speed, and consequently any fines they may have had to pay for their transgressions.

In a 3-0 ruling, the Court of Appeal found that traffic courts can change the documented speed to the speed with which offending driver was actually travelling — a procedure known as "amending up."

"Defendants have no vested right to insist on a trial only on the charge named on the certificate of offence. The prosecutor may thus exercise discretion by asking the court to 'amend up' the certificate," Justice John Laskin wrote in the ruling.

"A speeding charge may be 'amended up' only if the evidence at trial supports the amendment, the circumstances of the case warrant the amendment, the defendant is not prejudiced by the amendment and no injustice would be visited on the defendant by granting the amendment," said the ruling, which was the resolution of an appeal by the York Regional Municipality.

The case was set in motion after Robert Winlow was clocked driving at 130 km/h in a 100 km/h zone on Highway 400 in December 2006.

The officer ticketed Winlow at 115 km/h. Winlow refused to pay the fine and opted for a trial.

At the August 2007 trial, the officer testified that Winlow was driving at 130 km/h, but the justice of the peace refused the Crown's request to amend the ticket to show that. She convicted Winlow of driving 115 km/h, a decision upheld in March 2008 by Ontario Court Justice Ronald Minard. York Region had appealed that decision, and had requested Winlow be convicted for driving at 130 km/h.

The Court of Appeal dismissed the March 2008 ruling Thursday.