Re-Calibration is Main Issue Not Maintenance
Lawyers need to focus on the argument that regular re-calibration to manufacturer’s specifications is necessary to ensure scientific reliability.
The issue is not recent, repair, update, or maintenance but rather recent re-calibration. The calibration interval needs to be defined and followed. It needs to be relatively short, perhaps one year.
The concept of calibration interval can be found throughout the international literature.
Re-calibration also needs to include systems on the approved instrument other than ethyl alcohol quantitative analysis. Such other systems include breath flow, ambient fail threshold, interference threshold, and RFI threshold.
Note that in Jackson the instrument had been recently calibrated and in Vallentgoed the instrument had been recently re-calibrated.