When you see an ambulance or cop car on the road, many people think it's just common courtesy to move over to the side of the road. Not many drivers, however, realize that it's actually the law. You legally have to move over for ambulances, cop cars, and other emergencies vehicles.
This law also applies to emergency vehicles, tow trucks, and construction vehicles on the other side of the road. If a cop car is pulled over on your side of the road, you're legally required to -- when possible -- give a full lane's buffer for the vehicle in case of emergency. If you can't pull over to the side of the road there is some leeway. In situations where you physically cannot pull over, or allow a full lane's buffer, most states require you to slow down to a reasonable speed. Or in some counties, a fixed speed below the current speed limit is acceptable. These lives are vital to saving the lives of officers, construction workers, and drivers. On average roughly 200 people lose their lives every year due to drivers who are unaware of Move Over laws.