Montana · Handbook chapter 9 · 4 min read

Chapter 9: Alcohol, drugs and fitness to drive

Montana's rules on vision, fatigue, alcohol and BAC limits, refusing a test, first DUI penalties, open containers, reporting drunk drivers, other drugs, health, emotions and senior drivers.

Why this chapter matters

Alcohol is involved in about 40% of fatal crashes, and the manual calls drunk drivers the number one killer on Montana roads. Being fit to drive also means seeing well, being rested and being calm.

Vision and fatigue

• You need 20/40 or better in at least one eye; glasses or contacts may be worn for the test.
• If your license requires glasses, always wear them; keep a spare pair in the car.
• When tired, stop every two hours or so, avoid big meals and do not drive when you would normally be asleep.
• After 18 hours awake, driving skills are like those of an impaired driver.

How alcohol works

• Alcohol reaches your brain within about one minute and hits judgment and skill first, so you cannot tell when you have had too much.
• It slows reactions, blurs vision and makes it hard to judge speed and distance.
• The body processes about one drink per hour, and alcohol can still build up at that rate. Only time sobers you up.
• One drink is 1 1/2 ounces of 80-proof liquor, 12 ounces of commercial beer or a 5-ounce glass of wine. Craft beers and specialty drinks often hold more.
• New drivers are affected more than experienced ones.

Alcohol and the law

• You can also be arrested for driving under the influence below these levels.
• You must take a test when an officer asks; you can lose your license for refusing.
• A first conviction: a fine of $300 to $1,000 plus court costs, 1 to 60 days in jail, and a six-month license suspension. Later convictions are much worse.
• You must be 21 to buy or drink alcohol.

Open containers

Open alcohol may not be in the passenger area. Keep it in a locked glove or storage compartment, the trunk or cargo area, or behind the last upright seat in a vehicle with no trunk. Sealed, unopened containers are allowed, as are open containers in a camper's living quarters or with passengers of a bus, taxi or limousine.

Report a drunk driver

Call local police or the Montana Highway Patrol with a description and direction of travel, or call toll free 1-800-525-5555. You do not have to give your name.

Other drugs

• Cold, allergy and headache medicine, sedatives and many prescription drugs, including medical marijuana, can impair driving like alcohol.
• Pep pills and diet pills may make you feel alert at first, then nervous, dizzy and unfocused.
• A label warning about heavy machinery means do not drive. Never mix drugs with alcohol.

Health and emotions

• Even a cold or a stiff neck can affect driving.
• Epilepsy requires a physician's written statement that the condition is stable. Insulin users should not drive if there is any risk of going into shock.
• If you are angry or upset, give yourself time to cool off before driving.

Senior drivers

Vision, hearing and reaction time can fade slowly. Drivers who give up driving can turn in their license at a driver exam station; doing so more than six months before it is due for renewal gets you a free ID card.