The breath testing machine uses infrared light and a complicated computer program to determine what your breath alcohol level is. Then the breath alcohol level is converted to a blood alcohol level.
There are a number of issues with the breath machines. Simple things like body temp and lung volume can create vastly different results. Maintenance issues can produce errors. The machines are only calibrated to a single reference point and expected to produce correct results along a range without a calculation of a margin of error.
Avogadro’s law affects the veracity of every breath test conducted. Avogadro’s law states that, “equal volumes of all gases, at the same temperature and pressure, have the same number of molecules”. For a given mass of an ideal gas, the volume and amount (moles) of the gas are directly proportional if the temperature and pressure are constant.
This scientific law tells us that different volumes of expelled lung capacity, affected by different body temps, at differing pressures of force of blow, will directly affect the number and density of ethanol molecules in the sample tested by the machine.
You need to make sure your attorney understands the science as well as the procedure.