Alcohol, Drugs and the 0.05 Limit

Key points

1. Alcohol and impairing drugs are involved in about 40% of fatal crashes.

   Source: Handbook p. 51

   “Alcohol and other impairing drugs are involved in approximately 40% of all traffic crashes in which someone is killed yearly.”
   Utah Driver Handbook, Handbook p. 51

2. Vision is affected at 0.02 BAC for all drivers.

   Source: Handbook p. 51

   “Vision is impacted at 0.02 blood alcohol content (BAC) for all drivers.”
   Utah Driver Handbook, Handbook p. 51

3. Impairment starts with the first drink.

   Source: Handbook p. 51

   “Impairment starts with the first drink. Even one drink of alcohol can affect a person’s ability to operate a motor vehicle.”
   Utah Driver Handbook, Handbook p. 51

4. Over 0.05 BAC (0.04 for CDL drivers) you violate the law.

   Source: Handbook p. 52

   “If you are over 0.05 BAC (0.04 for CDL), you violate the law.”
   Utah Driver Handbook, Handbook p. 52

5. You also violate the law if you are impaired to the point of being unsafe, even below the legal limit.

   Source: Handbook p. 52

   “Utah law also states that driving is a violation if you are impaired to the degree that it is unsafe to operate a vehicle, even if you are under the legal limit.”
   Utah Driver Handbook, Handbook p. 52

6. Illegal, over the counter and prescribed drugs can all affect your driving like alcohol.

   Source: Handbook p. 51

   “Drugs can impact your driving and affect your reflexes, judgment, vision, and alertness, like alcohol.”
   Utah Driver Handbook, Handbook p. 51

7. Never let a friend or relative drive if they have been drinking.

   Source: Handbook p. 51

   “Never let a friend or relative drive if they have been drinking.”
   Utah Driver Handbook, Handbook p. 51

Numbers to know

3 questions from the Utah practice test

1. 1. A Utah driver has a BAC below 0.05 but is impaired enough to operate a vehicle unsafely. Is driving still a violation?

   1. No, a BAC below 0.05 always permits driving
   2. Yes, unsafe impairment can violate the law below the BAC limit
   3. Yes, but only if the driver holds a CDL
   4. No, unless the driver causes a collision
   Show answer

   Yes, unsafe impairment can violate the law below the BAC limit. Utah prohibits driving when impairment makes vehicle operation unsafe, including when the measured BAC is below the legal limit. Treating every reading below 0.05 as permission to drive ignores this separate impairment condition. A driver who cannot judge gaps or react reliably after drinking should arrange another ride rather than rely on a number. The practical cue is the inability to drive safely; a collision does not have to occur before the conduct can violate the law.

2. 2. Which pair of BAC figures does Utah’s handbook give for the general limit and the CDL limit, respectively?

   1. 0.10 BAC and 0.05 BAC
   2. 0.08 BAC and 0.04 BAC
   3. 0.05 BAC and 0.08 BAC
   4. 0.05 BAC and 0.04 BAC
   Show answer

   0.05 BAC and 0.04 BAC. The handbook identifies 0.05 BAC for the general rule and 0.04 for CDL. Using 0.08 for the first figure would miss Utah’s lower alcohol limit, even though that number may sound familiar. When studying the two figures, connect the smaller one with CDL rather than reversing their order. Neither figure is a target for drinking before driving: the same section also prohibits operating a vehicle when impairment makes driving unsafe below the numerical limit.

3. 3. Can taking just one alcoholic drink affect a person’s ability to drive, according to Utah’s handbook?

   1. No, impairment starts only after two drinks
   2. No, if the drink is consumed with a meal
   3. Only if the drink is combined with a prescription drug
   4. Yes, impairment starts with the first drink
   Show answer

   Yes, impairment starts with the first drink. Alcohol can affect driving ability beginning with the first drink. Waiting until a second drink to consider impairment leaves out the effect that may already be present after one. A small serving count therefore should not be used as reassurance before taking the driver’s seat. If you are deciding how to get home after a drink with dinner, arrange transportation with a sober driver. The practical decision is to avoid driving after alcohol rather than trying to detect impairment yourself.

Source: the Utah Driver Handbook, Section 10: Alcohol/Drugs and Driving. This lesson is a plain English summary, not the law itself; where it differs, the manual and the statute govern. Last checked 2026-09-27.