The measurand problem in breath alcohol testing.

Area of Science:

• Forensic Science
• Metrology
• Toxicology

Background:

• Breath alcohol testing is crucial for legal proceedings.
• Accurate interpretation of forensic measurements is vital for justice.
• Tests measure alcohol concentration, but the specific quantity (measurand) is legally defined.

Purpose of the Study:

• To explain the concept of the measurand in breath alcohol testing.
• To illustrate the 'measurand problem' and its implications.
• To highlight how variations in measurand definitions can undermine legal evidence.

Main Methods:

• Conceptual illustration of the measurand.
• Application of Hlastala's breath test paradigm.
• Integration of Gullberg's work on breath test uncertainty.

Main Results:

• Identical numerical breath alcohol test results can represent different quantities across jurisdictions.
• Statutory definitions of the measurand vary, leading to potential misinterpretation.
• Failure to account for the correct measurand compromises evidence-based conclusions.

Conclusions:

• The definition of the measurand is critical for accurate breath alcohol testing interpretation.
• Jurisdictional differences in measurand definitions pose a significant challenge.
• Proper accounting for the measurand is essential to validate forensic evidence.