What is the primary purpose of a portable breath test in DUI investigations?

• A. It provides a quick screen to indicate possible impairment.
• B. It substitutes for a chemical test.
• C. It determines the exact blood alcohol concentration.
• D. It can arrest a suspect automatically.

Answer: (A)

Portable breath tests are field screening tools used at the scene to quickly indicate whether a driver might be impaired by alcohol. The value lies in providing a rapid, preliminary indication that helps officers decide whether to pursue further testing or take appropriate action. It does not establish an exact BAC or serve as a substitute for a validated chemical test, and its readings can be influenced by factors like mouth alcohol, recent drinking, or device calibration. Arrest decisions and legal determinations rely on the follow-up evidentiary test and corroborating evidence, not solely on the portable reading.