You’re driving on a Southern California highway, trailing a driver who seems to be having trouble controlling the vehicle. You suspect the driver is drunk or on drugs, and while you are keeping your distance, you fear the driver is a danger to others on the road.

These are among the signs of a drunk or drugged driver on the road, according to MADD:

  1. Tailgating
  2. Weaving or drifting in and out of lanes
  3. Improper signaling
  4. Quickly accelerating or decelerating
  5. Stopping for no reason
  6. Almost hitting cars or other objects
  7. Slowly responding to traffic signals
  8. Traveling too slowly
  9. Driving without headlights at night
  10. Making illegal turns
  11. Driving on the wrong side of the road

Once you’ve witnessed one or more of those signs, what should you do? Continue by staying as far away from that other vehicle as you can. Don’t try to pass and stay back. Then, without doing anything that would put yourself at risk, try to gather as much information about the other vehicle as you can. What are the car manufacturer and the model of the vehicle? The color? That’s valuable information in case you can’t get close enough to see the license plate.

Finally, call 911. If you don’t have a hands-free option to make the call, pull over. Be prepared to give a full description of the vehicle, the road it is on and the direction it is traveling and the reasons you think the driver might be impaired.

Alcohol-impaired driving killed 10,511 people on U.S. roads in 2018, according to the National Safety Council. Your safety, and that of other drivers, is paramount. If you suspect a driver is impaired, based on the MADD guidelines, you could be saving a life if you call authorities.