In DUI cases, an accurate blood test result requires more than just the blood tester to be working properly. A reliable test results requires more than than what the machine (the blood tester) provides. As shown below, see the machine is just a fraction of the process need to obtain an accurate and reliable result.
Usually the government only puts safeguard in place to prevent machine errors. Consequently the majority of the blood testing process will go unchecked and subject to human error.