Two lanes and amber lights
The amber lights on this patrol vehicle are on. This is a two lane road. Traffic must slow down to 20MPH less than the posted speed limit.
A New State Law went into effect July 1st, 2003
Move Over, Slow Down

South Dakota State Statutes require motorists in South Dakota must stop when coming from any direction and approaching any stopped authorized emergency vehicle making use of red visual signals. The law now requires you to move over and slow down when passing any vehicle displaying amber or yellow flashing lights.

The law is aimed at reducing danger for these vehicles(such as patrol cars, other emergency vehicles, service vehicles and all of the traveling public that may have broken down on the highways of this state.) by being hit by passing vehicles.

Under the new law, motorists on South Dakota Interstates and other highways with two or more lanes traveling in the same direction as the vehicle, must merge into the lane farthest from the vehicle and proceed with caution, unless otherwise directed.

On two lane highways you must slow to a speed that is at least twenty miles per hour less than the posted speed limit or five miles per hour when the speed limit is posted at twenty miles per hour or less and proceed with caution, unless otherwise directed.

A violation of this law is a class 2 misdemeanor which is punishable by a fine of $200 and/or 60 days in jail.

Source South Dakota Codified Laws 32-31-6.1
The Move Over Law
Divided highway and amber lights
This vehicle is stopped on the interstate system by a patrol car with its amber lights on. In these situations traffic coming from the same direction must move over to the opposite lane.
divided highway red lights.
The red lights on this patrol car are on. This is on a divided highway. Vehicles traveling in the same direction must stop for the red lights unless otherwise directed.
This is an example of what we are trying to prevent. This patrol car was struck while on the shoulder of the highway. Please be considerate and give your fellow motorists the room they need.