Alcohol & Volatiles in Forensic Toxicology

EVIDENCE REVIEW

How to evaluate alcohol and volatile evidence

Alcohol and volatile findings must be evaluated from specimen collection through instrumental reporting. A useful review identifies the specimen source, collection time, tube type, preservative, storage history, analytical method, calibration range, quality controls, dilution steps, and reporting threshold. Blood, breath, urine, vitreous fluid, and tissue answer different questions and should not be treated as interchangeable measurements.

Interpretation also requires separation of measurement from inference. A reported concentration may support the presence or amount of a compound in a particular specimen, but questions about drinking history, timing, impairment, endogenous production, contamination, postmortem change, or causation require additional evidence. The guides below focus on the records and limitations that help distinguish a defensible analytical conclusion from an assumption.

Records that often matter include chromatograms, calibrator and control results, sequence tables, maintenance logs, repeat analyses, uncertainty information, specimen seals, and collection documentation. When breath testing is involved, instrument checks, observation procedures, environmental conditions, and agreement between replicate measurements may also matter. Reviewing those materials together helps identify whether the laboratory result is technically supported and whether its evidentiary use stays within the demonstrated capabilities of the method.