What should I do if there is a stopped vehicle with flashing lights, like a police car, at the side of the road?

Proceed with caution — it’s the law. When you approach a stationary vehicle on a highway with at least four lanes, two of which are designated for travel in the same direction as you, for the safety of your vehicle and others, cautiously with regard for the safety and traffic conditions, yield the right of way by making a lane change. You should make a lane change into the lane farthest from the stationary vehicle. If safe, move over! If such a lane change is not safe, proceed with caution and at a safe speed at least ten miles below the posted speed limit. 

Highway safety is always of the utmost importance. Violation of this law can result in conviction of a Class 1 misdemeanor that can be punished with jail time, a fine, and license suspension.