One of the scariest times that you need defensive driving techniques is when you encounter a drunk driver. If you see a driver that is weaving or drifting in their lane, they may be under the influence of alcohol or drugs. Other erratic driving behaviors may also be signs of drunk driving.
If you encounter a drunk driver, don’t try to pass them. Keep your distance. Stay behind the drunk driver and wait patiently. Leave even more following distance between you and the driver in question than you do in a normal circumstance. Passing the driver creates a danger for you. Stay behind, leave extra following distance and call the police.