West Australian police are unlikely to have the power to issue speeding infringements using results from new point-to-point cameras when the technology is installed on the main road between Perth and Bunbury.

Police do not yet have the legislative power to lay charges using results from the cameras, just months ahead of a trial of the technology on Forrest Highway.

The $1.5 million trial will be the state's first use of point-to-point cameras, which measure a driver's average speed between two different locations.

The technology is already widely used in other states, particularly in regional areas.

Legislation has been prepared

Attorney-General Michael Mischin told a budget estimates hearing legislation would soon be introduced to Parliament giving police the power to charge drivers with speeding using point-to-point cameras.

But legislation typically takes at least several months to progress through Parliament, which is also on the verge of breaking for the six-week winter recess.

"Potentially you could charge someone with a hoon offence or a dangerous or reckless driving offence with that information, but what you can't do is charge people with speeding until you get a change in the legislation," Police Commissioner Karl O'Callaghan told the hearing.

"It certainly could be used, in conjunction with other evidence, to prove a case of reckless, dangerous driving, or careless driving, but not speeding."

Labor's road safety spokeswoman Michelle Roberts said the Government had been talking about using point-to-point cameras for five years, and the process had taken far too long.

"The Barnett Government's delay here has already cost lives, we know that the evidence is there from road safety evidence that this technology saves lives," Ms Roberts said.

"It is incompetence of the highest order."

Senior police told the hearing there were not yet any estimates on revenue that could be generated from the cameras once they have the power to use them for speeding infringements.

But Mr Mischin said that was one of the reasons for the trial.

"The point of it would be to establish whether it is worth the effort down the track," Mr Mischin said.

Police said if the cameras were rolled out more broadly, they were likely to be in regional areas.