Three High Court judges will rule this summer on an appeal case which could overturn speeding convictions dating back a generation and open the floodgates for compensation running into tens of millions of pounds.

At the heart of the appeal is the alleged failure of the Home Office to follow its own procedures by specifying in law the equipment used for speed traps. Each type of camera or device, whether using radar, laser or other technology, was meant to be tested and then specifically prescribed by name in a Parliamentary Order.

The failure of civil servants to do so could render most of the speeding convictions over the past 19 years unsound, and judges at the Court of Appeal will rule on the test case this summer.

The case is seen as being of sufficient merit that legal aid has been awarded and counsel is being instructed.

A second argument in the case will be that similar bureaucratic sloppiness has left Scotland's motorway network stuck in a grey area in law, with the roads' precise status unclear and therefore the laws applying to them invalid.

This argument does not apply south of the Border, but the arguments about the legality of speed cameras does and that is to be tested in a similar test case in England brought by the same campaigner.

The case in Scotland is logged as Robbie the Pict v Procurator-Fiscal Annan, and relates to the campaigner being convicted of driving at 85mph on the M74. He told The Herald yesterday that his defence was that there was no speed limit on this stretch of road or any other motorway in Scotland because the subordinate legislation was never put in place to confirm in law the road's status.

His second line of defence is that no laser speed measuring device has been declared a prescribed device in the required Parliamentary Order, including the LTI 20-20 Speedscope used to convict him.

He also has a case before the English courts regarding the use of the Gatso camera, the most commonly used on Britain's road, which he argues has also not been properly prescribed.

The campaigner said: "This places under question all speeding convictions on motorways since their opening in Scotland, all speeding convictions based on speed measuring devices or cameras since 1991, and in particular all speeding fines or convictions based upon laser guns and their related cameras since their individual introduction. This is now a multi-million pound issue undermining every fine levied since 1991 and all the compensation which may be due as a result of wrongful prosecutions and convictions.

"The possible political fallout is of a significant order, starts with the Tory Home Secretary of 1991 Kenneth Baker, followed by Kenneth Clarke."