Portable breath test machines used by the San Francisco Police Department for DUI / Drunk Driving investigations and arrests apparently have not been properly tested for accuracy. There is now an investigation into the San Francisco Police Department's use of the machines. Records dating back to 2006 indicate the sample readings consistently matched actual tests which apparently is a mathematical impossibility. The investigation will have to go back to 2001 when the machines were first used by the SFPD. According to some reports, anywhere from hundreds to thousands of DUI / Drunk Driving convictions may have to be vacated. As a result of this irregularity, the San Francisco Police Department has stopped using the portable breath testing machines. I've always maintained that breath testing is based on voodoo science. This is just another of a long line of examples of inaccuracies of breath testing.