The issue has been highlighted after Christchurch man Peter Fiddler was given a ticket for allegedly driving at 113kmh while heading south of Christchurch on December 22 last year.
He disputed his speed at the scene and when he asked the officer to produce evidence from his radar-gun, the "clocked speed" had been wiped.
Fiddler complained to the Police Infringement Bureau, saying there was no evidence he was travelling beyond the speed limit, but the police refused to waive his ticket saying: "There is no legal requirement for you to be shown a readout or even for the readout to be locked".
Fiddler said this week: "I didn't think it was fair and I tried to discuss it with the officer but he didn't want to know. I tried to challenge it ... (but) I weighed up the costs and I just couldn't afford a day off work to go to court and defend it."
Exasperated, Fiddler paid the fine but contacted The Press, concerned at what he claims are unfair police rules.
"They could just make up a speed and write the ticket. It's ridiculous," he said.
Recent decisions show the courts are backing motorists such as Fiddler, waiving fines for those who challenge police unable to provide evidence of speeding.
Christchurch man Bryan McHerron took the matter to court in September last year after police were unable to produce radar evidence at the scene of his ticket.
An officer allegedly clocked McHerron travelling 121kmh in a passing lane near Amberley, but lost the radar record seconds after the incident and was unable to show McHerron any evidence as he wrote out the ticket.
McHerron went to court, admitting he was probably travelling at more than 100kmh, but denied it was 121kmh.
The Rangiora District Court ruled in McHerron's favour, with two Justices of the Peace saying: "This issue for us is whether there has been a burden of proof beyond reasonable doubt regarding the excessive speed ... to cast light or doubt on the actual speed under consideration and in the interests of justice we think it is not unreasonable for the driver to see the actual locked-in radar speed.
"In this instance it was not available and does create an element of doubt to the actual speed for the defendant."
The decision was based on a similar High Court ruling in 1996 when a motorcyclist on the West Coast successfully defended an alleged radar reading of 126kmh after the officer could not produce evidence of the speed quoted on the ticket.
McHerron now claims his ticket was the result of a Government-pushed, revenue-grab which is forcing police to become "quite unethical".
"It borders on harassment what they do. It's a recipe for fraud because at the end of the day, the average person just accepts what the police have said. Motorists have got some rights and I believe the police are taking those rights away."
Canterbury Road Policing manager Derek Erasmus reiterated the police stance, saying an officer did not have to lock a speed in.
"Best practice indicates that we do it because it removes those arguments further down the track but sometimes ... it's not physically possible to lock it in."
An officer may have to act quickly if a driver was coming around a corner and would not have time to lock the speed in, Erasmus said.
"If a person doesn't like it, you can dispute it through the court process. It's no different from the vast majority of police cases disputed in court.
"It comes through to an issue of credibility. At the end of the day (motorists) have the recourse of taking it to court and the evidence is weighed in an independent forum."
A senior police official said complaints over lack of evidence "presupposed police were liars".
"These are sworn officers who gain no benefit from making things up."
A police spokeswoman said police stood by their legal stance and any appeal against a ticket was a decision for the court, not police.