When do you have to activate your hazard lights?

You should activate your hazard lights when your vehicle is disabled or experiencing a mechanical issue that requires you to stop on the side of the road. They can also be used when you're temporarily stopped in a dangerous location, such as during an emergency or when waiting for assistance. Additionally, using hazard lights is appropriate in situations where visibility is severely reduced, like during heavy rain or fog. Always check local laws, as regulations may vary regarding their use.