Final answer:
Alcohol affects driving by decreasing reaction time, lowering alertness and visual sharpness, and impairing motor control, which increases the risk of accidents. This is why driving with a BAC of 0.08% or higher is illegal.
Step-by-step explanation:
Alcohol consumption significantly impairs multiple aspects of cognitive and motor functioning, which greatly affects attention while driving. After consuming alcohol, an individual may experience a reduction in reaction time and visual acuity, alongside lower levels of alertness and a reduced ability to control behavior. This can lead to difficulty coordinating movements, a key reason why field sobriety tests often include tasks such as walking in a straight line, which the cerebellum—sensitive to ethanol—struggles to manage while under the influence. Law enforcement employs tools like the Breathalyzer to measure a driver's blood alcohol concentration (BAC), which can provide an estimate of their level of intoxication and potential impairment.
Regarding its effect on driving, alcohol may lead to feeling sedated at higher doses and can cause a complete loss of consciousness or memory blackouts at excessive levels of consumption. These effects hugely increase the risk of accidents since they diminish a driver's ability to operate a vehicle safely. Therefore, it is against the law to drive with a BAC of 0.08% or higher in the majority of US states.