Quick answer: Breath tests are faster but indirect — they estimate blood alcohol from breath and are sensitive to calibration, timing, and physiology. Blood tests measure alcohol directly but depend on proper draws, storage, and lab work. Both can be wrong, and both can be challenged.
This video compares the two chemical tests used in Texas DWI cases: how each works, when police use them, and — most importantly — how each one fails.
For breath: partition-ratio assumptions, mouth alcohol, residual contamination, and machine calibration. For blood: chain of custody, fermentation in improperly stored vials, and lab analyst errors. The takeaway: a test number is the start of the state’s case, not the end of yours.
Related reading: What is the difference between DWI breath and blood tests?
Contact Stephen T. Bowling, DWI & Criminal Defense Attorneys for a free consultation — we answer these questions about your specific case, at no cost and no obligation.
