Dazzle occurs when oncoming headlights are not dipped, or on low beam, and you have a hard time seeing because of the brightness of the lights. The rules are to “dip your beams in good time” so you don’t dazzle oncoming drivers. If you are dazzled, you may have to slow down, but don’t brake too hard, as there might be a vehicle behind you. There is also such a thing as an “Anti-dazzle position” on your interior mirror. Here’s the official line from the Handbook:
When your headlights are on full beam,
- dip early enough to avoid dazzling oncoming drivers, but not too early
- Check the left-hand verge before you dip.
If you are dazzled by oncoming vehicles, slow down and , if necessary, stop. Don’t look directly at oncoming headlights. Don’t retaliate by leaving your lights on full beam and dazzling the oncoming driver. (p.271)