The recent case in which I proved that the speed gun used by Northern Constabulary, and most police forces in the UK, was not reliable deserves some thought by all drivers. It has serious implications for us all and the many calls made to me show that it is widely misunderstood.

What the decision does not do is allow anyone to appeal any convictions they may have for speeding. Nor can it be used as a defence in any future prosecution. This is a matter of Law. The decision was in one case before one Sheriff and does not, and cannot, form a legal precedent for any other case.

However, it cannot, and must not, be simply ignored as appears to be the response of both Northern Constabulary and Crown Office.

My client, Mr M, was driving his Subaru Impreza WRX north on the A9 dual carriageway at Daviot, just south of Inverness in the gathering dusk in August last year. Traffic officers of Northern Constabulary were monitoring the speed of traffic using a Pro Laser 111 speed gun. They recorded him travelling at 132 mph in a 70 mph limit and ultimately the Procurator Fiscal at Inverness prosecuted him for dangerous driving.

The officers gave evidence on oath that the speed gun had been calibrated properly, both before, and after, catching Mr M. They explained to the court that it is impossible for the gun to develop a fault and still give a reading. They obtained the reading of 132 mph and showed it to Mr M.

However Mr M’s car was an import directly from Japan fitted with a speed restricting device, as all cars for the Japanese home market have to be by law. I was able to prove that that car could not drive at more than 107 mph and yet the Pro Laser 111 had given, what was clearly therefore, a very high, false reading of 132 mph.

In other words this speed gun was positively shown not to be reliable on that occasion. No other explanation is tenable.

Had my client been convicted of dangerous driving, he would have been disqualified for at least a year, required to sit an extended test and been liable to be sent to prison for up to 6 months or be fined up to £5,000 or both. Not only are these heavy penalties, such a conviction would also have had serious implications for his car insurance premiums.

In the very unusual circumstances of this case, I was able to prove a defence ie that the car could not have been travelling at anything like the claimed speed. The claimed speed is more than 23% faster than it could reach flat out. The difference could well have resulted in a conviction for dangerous driving when he simply was not.

So what have the Police and Crown Office done about it? Absolutely nothing. What do they intend to do? Again, absolutely nothing. Both are content, according to their public statements, to continue to use this machine and prosecute people for the speeds shown on it. They are prepared to brazen it out claiming that a machine, which has been proven to be faulty, is always accurate and reliable.

They may suggest that this was a one-off. On what basis? It gave a reading that it could not have obtained, we are assured, if working properly. We are told that cannot happen. Well, it did. How many other times was, or will, it be wrong?

This could happen to you if the investigating and prosecuting authorities continue to pretend to be ostriches. You are unlikely to be able to disprove their case.

If neither the Police nor the Crown Office are prepared to face up to the consequences and implications of Mr M’s case, then they must be forced to do so by the outcry from motorists and anyone interested in justice. Write to your MSPs now. The Justice Minister and Lord Advocate are answerable to the Scottish Parliament.

Furthermore unless they can give a satisfactory explanation of how this error happened and what steps have been taken to guarantee that it will not happen again, every allegation of speeding using Pro Laser must be questionable. The Crown should be reviewing any conviction obtained using this device. It appears they are unwilling to do so. Write to your MSP if you have been affected.