Internal police documents are raising doubts about the precision of some roadside breathalyzers used by B.C. police to catch drunk drivers.

Vancouver lawyer Paul Doroshenko filed Access to Information requests with police departments across the province and found that the screening devices aren't always accurate.

He discovered that police in Port Moody were using the same chemical solution to perform too many calibration tests.

"The standards that are accepted in Canada say that you can do 16 tests with one bottle of solution. They were doing at least 18 and up to 50 with each bottle," he told CTV News.

An investigation is now being conducted by New Westminster police into how the Port Moody department uses the tools.

Inspection documents from the Vancouver Police Department show some erratic readings on those tools.

"Sometimes they grossly inflate the reading that should be reflected on the unit," Doroshenko said.

During a monthly calibration in February, one machine calibrated with a standard chemical solution showed a reading of .117 -- when it should have registered .082.

If the reading had been off by that much on the road, it might have meant the difference between the "warning" level and a "fail."

"We don't know how many people blew into it -- how many people blew a fail who were not actually over the limit," Doroshenko said.

Vancouver police admit that such an exaggerated reading during inspection would be a problem.

"We would send that for repair. The reality is that it would be difficult to know when that instrument came out of calibration," Const. Jana McGuinness said.

She added that increasing the frequency of inspections for the devices would be a "good step" for the department.

McGuinness points out that drivers who are concerned about unfair tests have the legal right to request a second test taken on a different instrument.

Last week, a B.C. judge ruled that the province's new policy of an immediate 90-day driving suspension for drivers who register a blood alcohol level above .08 constitutes an infringement of Charter rights.

Government officials say all the administrative appeals being reviewed by the Office of the Superintendent of Motor Vehicles have been adjourned until further analysis of the impacts of the decision can be completed.

With a report from CTV British Columbia's Mi-Jung Lee