The Alco-Sensor V is the newest version of a breathalyzer made by Intoximeters, a St. Louis based company. Officers use them in the field in addition to physical sobriety tests. The Santa Clara County District Attorney's Office is now reviewing arrests in which officers used the machine.
"That is, for the San Jose Police Department, about 865 cases, and we're still reviewing how many cases involving the Palo Alto Police Department," said Santa Clara County District Attorney James Gibbons-Shapiro.
Prosecutors say those are the only two police departments in the county that have been using the Alco-Sensor V. Palo Alto police bought the devices in February of last year. Officers reported repeated problems with condensation in the machine.
"So when the next person came along, any alcohol from the previous person might have been captured inside the machine and a second person may come back with a false report," said Palo Alto Police Lt. Sandra Brown.
Palo Alto went back to using the older model breathalyzer in December when it returned all the new devices to the company. The department says it alerted the district attorney several weeks ago when the company confirmed the new models were defective. That is when the district attorney told San Jose police to also stop using them.
Santa Clara County public defender Mary Greenwood says DUI cases can be re-opened again even if there's been a conviction.
"Of course, you can't give that person back their days of liberty that were lost, but there can be recompense in other ways," said Greenwood. "Also, their record can be cleared."
Prosecutors point out that most DUI suspects take a blood test or blow into a more sophisticated breathalyzer at the police station, which is the main evidence used in court. But ABC7 legal analyst Dean Johnson says the field breathalyzer test can be important in some cases.
"In a close case it can be the critical piece of evidence because it's the first objective measure that you have of a driver's blood alcohol level," said Johnson.
San Jose police say they have gone back to using the older version of the breathalyzers, as did Palo Alto police.
Intoximeters did not return calls by ABC7.