Question 1

The per-se BAC limit for adult, non-commercial Texas drivers is:

Accepted Answer

0.08%. 0.08% under Tx. Penal Code §49.04. Functional intoxication can be charged at any BAC.

Question 2

For Texas commercial driver license (CDL) holders operating a commercial vehicle, the BAC limit is:

Accepted Answer

0.04%. 0.04% for CDL holders operating a commercial vehicle.

Question 3

For Texas drivers under 21, the BAC threshold is:

Accepted Answer

Zero tolerance for any detectable amount. Texas Alcoholic Beverage Code applies zero tolerance to drivers under 21 — any detectable amount can support a charge.

Question 4

Driving while impaired by a legally prescribed medication in Texas:

Accepted Answer

Can still be charged as DWI. Texas DWI covers any substance that impairs the driver, including legally prescribed medications.

Question 5

A first-offense Texas DWI with a BAC of 0.15% or higher is charged as:

Accepted Answer

A Class A misdemeanor. 0.15% or higher elevates a first-offense DWI to a Class A misdemeanor with steeper penalties.

Question 6

Being awake for 18 hours produces reaction-time impairment roughly equivalent to a BAC of:

Accepted Answer

0.05%. Roughly 0.05% BAC. 24 hours awake puts you near 0.10% BAC equivalent.

Question 7

Texas's open container law makes it illegal to possess an open alcohol container in:

Accepted Answer

The passenger area of a vehicle on a public highway, even if the engine is off. Tx. Penal Code §49.031 — the passenger area on a public highway, even when stopped.

Question 8

An ignition interlock device prevents the vehicle from starting unless:

Accepted Answer

The driver provides a clean breath sample. An interlock requires a clean breath sample before the engine starts (Tx. Code Crim. Proc. Art. 17.441).

Question 9

The most effective countermeasure for drowsy driving is:

Accepted Answer

Sleep. Sleep is the only thing that actually restores alertness. Caffeine masks tiredness briefly but doesn't fix it.

Question 10

Functional intoxication (loss of normal use of mental or physical faculties) under Texas DWI law applies:

Accepted Answer

At any BAC, including 0%. Tx. Penal Code §49.01 defines intoxication two ways: per-se (0.08%) AND functional (loss of normal use). The functional definition can apply at any BAC.

Alcohol, Drugs & Impairment

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