One in three drivers who disputed a fine in the ACT had their penalties waived last financial year, forcing the Government to refund $1.6million to falsely accused Canberrans.

About one of every six drivers caught parking illegally, speeding, or committing other traffic offences disputed their fines, according to statistics issued by the Justice and Community Safety Directorate.

Authorities are forced to devote a considerable amount of resources into investigating each of the 26,087 challenged fines.

ACT Policing alone spent almost $500,000 trying to work out whether each traffic dispute was valid.

NRMA director Alan Evans said the sheer number of challenges suggested deep flaws with the territory's infringement system.

Mr Evans questioned whether parking inspectors were being adequately trained and whether signs were easy enough for motorists to read.

He said the fact that camera infringement notices were being refunded indicated fixed speed cameras were not a ''foolproof'' technology.

''That's a concerning feature to me, that on fixed speed cameras, people are seeking a review and it's been found that they haven't transgressed,'' he said.

''That suggest to me there might be some faults in the system that are not being made public.''

Monash University Accident Research Centre's Professor Max Cameron said it was surprising that fixed and mobile camera technology had been proved wrong on so many cases.

Professor Cameron said the technology had proven highly accurate in most other jurisdictions. ''There are very few examples, at least in other states and territories, where people escape camera fines,'' he said. ''There's some classic counter-examples, but they're very rare.''

To have a fine overturned, drivers either apply to ACT Policing to have their infringement notice withdrawn, or dispute the fine directly, which generally takes the matter to court.

Professor Cameron said punishment was an important method of altering the behaviour and attitudes of traffic offenders.

By successfully disputing traffic fines, he said, drivers were more likely to think they could get away with other transgressions.

''What the research is pointing to is that it is very important that people are punished for their traffic offences, no matter how minor they are,'' he said.

The NRMA has also used the statistics to question the introduction of point-to-point speed cameras in the ACT.

A set of cameras are being set up to monitor Hindmarsh Drive, from Yamba Drive to the Monaro Highway, while other cameras will be set up on sites including the Barton Highway.

Mr Evans said the technology was still imperfect, and would open up the door for more disputes over fines.

''We've expressed our concerns about point-to-points, we think there are inherent flaws in that system,'' he said. ''We're becoming too reliant on the technology, to the exclusion of having the most effective method, as I've always said, a visible police presence.''