Which practice is least useful for assessing impairment in a crash investigation?

• A. Blood Alcohol Concentration
• B. Field sobriety tests
• C. Tire wear inspection
• D. Vehicle speed analysis

Answer: (C)

Understanding impairment in crash investigations centers on whether the driver’s abilities were compromised at the time of the crash. The most direct evidence comes from chemical and performance indicators: blood alcohol concentration provides a measurable level of intoxication, and field sobriety tests assess observable deficits in balance, coordination, and attention that point to impairment. Vehicle speed analysis looks at how speed contributed to the crash and helps explain dynamics, which is about the driving behavior but not the driver’s impairment per se. Tire wear inspection, while important for assessing vehicle condition and potential traction issues, does not indicate whether the driver was impaired at the moment of impact. It informs maintenance or mechanical factors, not impairment, making it the least useful for assessing impairment among the options.