DWI Lawyer in Raleigh, NC, Talks Breath Testing and Henry’s Law

This is Part 14 of our weekly North Carolina Criminal Defense video blog: “Breath Testing and Henry’s Law


Henry’s law assumes that the alcohol that is in your blood if it was in a closed container that over time the amount of alcohol in your blood would go into the air above your blood or into the lungs. That really only applies when it is a closed area.

The way gas chromatography works is that they take a sample of your blood, put it into a test tube, that test tube is capped, and it’s put into a machine and under a certain temperature the science says that the alcohol that’s in that blood sample will leach into the head space of that vial and that eventually they will reach equilibrium.

The human body isn’t like that. Our lungs aren’t a closed system. There is nothing that is like that test tube where it’s closed off. To some extent, it doesn’t work that way in terms of the human body.

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