Texas Car / Permit practice question · Alcohol & Drugs

What is the effect of marijuana on a person's ability to drive?

Answer choices

• It is only a problem when combined with alcohol
• It slows reactions but leaves judgment intact
• Even ordinary social amounts dull concentration, judgment, and the senses a driver depends on— Correct answer
• It affects only people who rarely use it

Why this is the answer

Research cited in the handbook says that marijuana, even at typical social doses, can affect concentration, judgment, and the sensory and perceptual skills careful driving needs. People under its influence have impaired sensory and perceptual abilities. So it is a problem on its own, whether or not alcohol is also involved.

Source: Texas Driver Handbook — Drugs and Driving

Content reviewed against official driver handbooks · August 12, 2026