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Topic 6 · Section 10

The Dangers of Impaired Driving

Before getting into the rules, let’s understand why driving under the influence is so dangerous.


🧠 Impaired Judgment

  • Alcohol and many drugs dull your decision-making.
  • You might misjudge distances, run yellow lights, or take unsafe risks.
  • Impairment leads to bad calls behind the wheel, even when you think you’re okay.

🐌 Slower Reaction Time

  • Even small amounts of alcohol slow your reflexes.
  • At 60 mph, a half-second delay means 44 feet extra traveled — which could be the difference between a near miss and a crash.
  • Impaired drivers often brake too late to avoid hazards.

🤹‍♂️ Reduced Coordination

  • Alcohol messes with hand-eye-foot coordination.
  • This makes it harder to steer smoothly, stay in your lane, or brake correctly.
  • That’s why drunk drivers often weave or stop unpredictably.

👓 Blurred Vision

  • Alcohol slows eye muscle control and can cause:
    • Blurry or double vision
    • Tunnel vision
    • Poor depth perception

😴 Drowsiness

  • Alcohol is a depressant, meaning it can make you sleepy.
  • Many DUI crashes happen late at night, combining alcohol and fatigue — a deadly mix.

😎 False Confidence

  • While your skills get worse, your confidence goes up.
  • That’s the danger: you feel brave and capable while being slower and clumsier.
  • “I’m fine to drive” is a common — and often fatal — misconception.

💊 Other Drugs Also Impair Driving

Marijuana

  • Slows reaction time and impairs coordination.
  • Makes drivers too relaxed, more distracted, and prone to weaving.

Prescription Meds

  • Opioids, sedatives (like Xanax), and strong cold meds can cause:
    • Drowsiness
    • Confusion
    • Delayed response

Over-the-Counter Meds

  • Some antihistamines or cold meds cause foggy thinking and drowsiness.

Stimulants

  • Drugs like meth or cocaine can make drivers:
    • Aggressive
    • Reckless
    • Unpredictable
  • When the high crashes, so does attention and coordination.

⚠️ Consequences of Impaired Driving

  • DUI crashes are more likely to result in serious injury or death.
  • Why? Impairment causes:
    • High speeds
    • Late or no braking
    • Failure to swerve or avoid hazards
  • You risk your life, your passengers’ lives, and the lives of others on the road.

✅ The Bottom Line

  • Any substance that alters your mind makes you unfit to drive.
  • Legally, a BAC below 0.08% might be allowed — but even lower levels can impair.
  • The only safe BAC is 0.00% when getting behind the wheel.

Check you have it

107 practice questions cover alcohol, drugs, and driving (dui laws), each explaining the reasoning behind its answer.

Practise this topic

Source: California Driver's Handbook (DL 600, rev. 6/2025). Edited by Fernando Aguilera. Aprobify is not affiliated with the California DMV.

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