Being stuck on the highway behind slow drivers can be frustrating, but using the left lane as your primary means of travel can be illegal too.

Colorado’s “Left Lane Law” went into effect in 2004, with the Colorado State Patrol once again reminding drivers that the left lane should only be used as a passing lane.

The law only applies to highways with a speed limit of 65 mph or more and if drivers are caught violating this, they could be cited and fined.

“It’s when they’re traveling in that left lane for a mile or two, and they’re just cruising that lane, not getting over,” said Trooper Mike Prock with Colorado State Patrol.

Trooper Prock said the Left Lane Law is often violated on northbound Interstate 25 from the Interquest exit on, when the highway narrows from three lanes to two. According to CSP, it’s important to move over for first responders.

“If we can keep those lanes open, response increases, medical attention increases, we can get the highway cleared up more quickly,” said Capt. Brian Vaughan with the Colorado Springs Fire Department.

According to CSP, depending on how many times a person has been pulled over for this, citations can run drivers up to $100.