Don't Drink and Drive.

According to MADD (Mothers Against Drunk Driving)

How to spot a drunk or drugged driver

While, we’re not suggesting you ever take the law into your own hands, or put yourself in danger, your vigilance on the road can help keep our roadways safe—for you, your loved ones and your neighbors.

Here are a few signs that a fellow motorist may be driving while impaired:

1. Quick acceleration or deceleration
2. Tailgating
3. Weaving or zig-zagging across the road
4. Driving anywhere other than on a road designated for vehicles
5. Almost striking an object, curb, or vehicle
6. Stopping without cause or erratic braking
7. Drifting in and out of traffic lanes
8. Signaling that is inconsistent with driving actions
9. Slow response to traffic signals (e.g. sudden stop or delayed start)
10. Straddling the center lane marker
11. Driving with headlights off at night
12. Swerving
13. Driving slower than 10 mph below the speed limit
14. Turning abruptly or illegally
15. Driving into opposing traffic on the wrong side of the road