Part of self-driving-car development involves teaching these vehicles to respond in certain ways to specific stimuli. Sure, an autonomous car might be able to navigate a road, but what if there's an emergency vehicle coming down the street? One of Google's patents addresses exactly that.
The patent, which was submitted back in 2014 but published this month, deals with a system for real-time detection of emergency vehicles. It uses the unique flashing pattern from emergency lights, which signals to the self-driving car that action needs to be taken. That action will usually involve pulling over and stopping until the emergency vehicle passes.
Of course, the correct response doesn't always involve pulling over to the side the second the cherries and berries are spotted. If the car's driving itself down the highway and a police officer has somebody pulled over up ahead, pulling over isn't the right thing to do. There will likely be all sorts of logic involved to tell the car how to react in other situations involving emergency lights.
As it stands, most (if not all) municipalities have rules regarding what color of lights you can put on your car. You're not allowed to add certain colors, like blue or red, because they're reserved for emergency vehicles, and impersonating an emergency vehicle is a pretty serious crime. I imagine it will only get more serious once autonomous cars start relying on those lights to function properly.