DENVER (KDVR) — Picture this: you’re cruising down the highway and someone passes you. After that, they hang out in the left lane while keeping others from getting around.

That scenario can be very frustrating for many drivers. But is it illegal? In certain situations, yes.

Left lane law

Colorado has a left lane law which is used to help ease congestion and improve traffic flow, especially during peak travel periods.

“A person shall not drive a motor vehicle in the passing lane of a highway if the speed limit is 65 miles per hour or more unless such person is passing other motor vehicles that are in a non-passing lane or turning left, or unless the volume of traffic does not permit the motor vehicle to safely merge into a non-passing lane,” Colorado law states.

In short, that means that if you’re on a highway with a speed limit of 65 mph or more, the left lane law applies unless the volume of traffic does not allow a driver to safely merge into a non-passing lane.

Is there a fine for violating the left lane law?

CSP said that if a trooper pulls over a driver for violating the left lane law, the penalty for the citation is $41.20. A driver will also receive three points against their driver’s license, which can be reduced to two points if the penalty is mailed within 20 days.

Can you pass on a shoulder?

Colorado law does not allow drivers to pass someone on the shoulder.