Colorado Legalized Lane Filtering on August 7, 2024. Lane Splitting Remains Illegal. The Difference Between Those Two Sentences Could Define Your Entire Case.
Lane filtering is legal in Colorado under SB24-079, signed by Governor Polis on April 4, 2024 (Colorado General Assembly, SB24-079), and effective August 7, 2024. The law allows two-wheeled motorcyclists to pass between lanes of completely stopped traffic at no more than 15 mph. Lane splitting, which involves riding between lanes of moving traffic, remains illegal in Colorado. If you were injured while lane filtering legally, or if you were hit by a vehicle whose driver did not expect a motorcycle between lanes, the law protects your right to compensation. If you were lane splitting in moving traffic, the legal analysis is more complicated, but you may still have a claim.
What Colorado’s Lane Filtering Law Actually Says
SB24-079 amended C.R.S. § 42-4-1503 to authorize a two-wheeled motorcycle to overtake or pass another motor vehicle in the same lane when specific conditions are all met simultaneously. The Colorado State Patrol published a plain-language summary of the requirements and recommendations (CSP, August 2024):
All traffic in the rider’s lane and adjacent lanes moving in the same direction must be at a complete stop.
All traffic in the same lane as the motorcycle and all traffic in adjacent same-direction lanes must come to a complete stop before the motorcycle may filter through. This is the most important condition for legal motorcycle filtering. If vehicles are moving anywhere in this area, the motorcyclist may not filter through.
The lane must be wide enough to fit the vehicle and motorcycle while passing.
The lane must have adequate width so that both the motorcycle and vehicle can pass through safely. It is the motorcyclist’s duty to determine whether there is enough room for both the motorcycle and vehicle to safely pass through the gap.
The motorcycle must travel at 15 mph or less.
The motorcycle may not exceed 15 mph while filtering through. UC Berkeley SafeTREC research has shown that when the speed difference between a motorcycle and other traffic exceeds 15 mph, the risk of injury to the motorcyclist increases dramatically.
The rider must pass on the left.
Passing on the right shoulder or to the right of a vehicle in the farthest right-hand lane on a non-limited-access highway is prohibited.
The rider must not enter a lane of traffic moving in the opposite direction.
When stopped vehicles begin to move, the motorcyclist must stop passing and merge back into the lane.
The rider must be at least 18 years old with a valid motorcycle endorsement.
The law includes a sunset provision: it automatically repeals on September 1, 2027. Before repeal, CDOT is required to analyze safety data and issue a report to the General Assembly. Colorado joins Utah, Montana, Arizona, and California as states that permit some form of lane filtering or splitting (American Motorcyclist Association, August 2024).
Lane Filtering vs. Lane Splitting: The Difference That Determines Your Case
The distinction between lane filtering and lane splitting is not semantic. It is the difference between a legal maneuver and a traffic violation.
| LANE FILTERING (Legal) | LANE SPLITTING (Illegal) | |
|---|---|---|
| Traffic status | All surrounding traffic STOPPED | Traffic moving at any speed |
| Rider speed | 15 mph maximum | No limit (matches or exceeds flow) |
| Direction | Pass on LEFT side only | Either side |
| Shoulder use | NOT permitted on right shoulder | Not applicable |
| Rider age | 18+ with valid motorcycle endorsement (general requirement) | Not applicable (illegal) |
| When traffic moves | Must STOP filtering and merge back | Can continue (illegal regardless) |
| Colorado law | SB24-079 (effective Aug. 7, 2024) | Prohibited under C.R.S. § 42-4-1503 |
| Sunset provision | Auto-repeals September 1, 2027 | Permanently prohibited |
If you were filtering through stopped traffic at 15 mph or less and a driver opened their door, changed lanes without looking, or pulled out of a parking position into your path, you were operating within the law. The driver who hit you was not. That distinction is the foundation of your case.
Why Colorado Legalized Lane Filtering: The Safety Case
Lane filtering was not legalized because riders lobbied for convenience. It was legalized because data showed it could save lives. The primary safety rationale is reducing rear-end collisions. When a motorcycle sits in stopped traffic behind a car, the rider is exposed to the full impact of any vehicle that fails to stop behind them. A motorcycle offers zero rear-end crash protection. No crumple zones. No airbags. No headrests.
In a review of just under 6000 motorcycle crashes in California from 2012 through 2013, SafeTREC at the University of California-Berkeley, directed by Dr. Thomas Rice, reported that motorcyclists engaging in lane-spliting had about half the odds of being rear-end struck by an automobile as those not engaged in lane-spliting (2.6% vs. 4.6%). Lane-splitting motorcyclist involved in crashes had lower incidence of head injuries (9% vs. 17%), torso injuries (19% vs. 29%), and fatalities (1.2% vs. 3%) (UC Berkeley SafeTREC, May 2015) . The most important conclusion is that the risk of injury for motorcyclists rose dramatically only when there was a difference in speed of 15 mph or greater between the motorcycle and the traffic in all lanes around it — the very same filter speed limit that was selected by Colorado.
CDOT explicitly cited this safety rationale when publishing guidance on the new law: “This new law could go a long way in saving lives: it prevents motorcycles from getting hit from behind by much larger vehicles, which can cause serious, if not fatal, injuries to motorcycle riders”(CDOT, June 2024).
How Lane Filtering Crashes Happen and Who Is at Fault
Driver Opens a Door into a Filtering Rider
A driver in stopped traffic opens their door without checking for a motorcycle passing on the left. The rider, traveling at or below 15 mph between stopped lanes, strikes the door. Under Colorado law, the filtering rider is operating legally. The driver who opened the door into the travel path of a legally operating vehicle is negligent. Colorado’s statute requiring safe opening of vehicle doors, C.R.S. § 42-4-1207, requires that no person open a vehicle door on the traffic side unless it is reasonably safe to do so.
Driver Changes Lanes into a Filtering Rider
Traffic is stopped. A driver in one lane decides to change lanes, perhaps to position for a turn or to move into what they perceive as a shorter queue. They do not check for a motorcycle filtering between the lanes. The motorcycle, operating legally at 15 mph or less, is struck by the lane-changing vehicle. The lane-changing driver failed to check their mirrors and blind spots before moving. The motorcyclist had a legal right to be where they were.
Traffic Begins Moving While Rider Is Filtering
This is the gray zone. The law requires riders to stop filtering when traffic begins to move. “Begins to move” is not defined with precision. If a rider is mid-filter when a light turns green and surrounding vehicles start accelerating, the rider’s obligation to merge back creates a moment of vulnerability. A vehicle accelerating from behind or beside the rider may close the gap the rider needs to merge. Fault in this scenario is fact-dependent: was the rider making a reasonable effort to merge? Did the surrounding driver accelerate without checking for the filtering motorcycle? Accident reconstruction and witness testimony become critical.
Road Rage Retaliation Against a Filtering Rider
Colorado drivers who are unaware of the new law or hostile to it may intentionally block, crowd, or swerve at a legally filtering motorcycle. As Col. Matthew C. Packard of the Colorado State Patrol noted, “It’s up to the rider to assess the scene ahead to determine if the conditions are safe and legal to filter.” But a driver who intentionally obstructs or assaults a motorcyclist is committing a separate violation, and potentially a criminal act. Dashcam or GoPro footage is the most powerful evidence in these cases.
What to Do If You Are Injured While Lane Filtering in Colorado
Document your speed.
If you were using a GPS-enabled device, action camera, or motorcycle equipped with a speedometer, save this information as soon as possible. The first thing the defense will challenge about your compliance with the 15 mph limit is your speed.
Confirm traffic was stopped.
Witness statements, dashcam video of other traffic in your lane and adjacent lanes, and traffic light timing records are examples of evidence that can confirm traffic was completely stopped before you began to filter.
Preserve surveillance footage.
Traffic cameras at intersections where lane filtering typically occurs, including stoplights and congested highway on-ramps, may capture the crash. This footage can be overwritten within 48 to 72 hours.
Do not admit fault or apologize at the scene.
Lane filtering is legal. If you were operating within the law’s requirements, you did nothing wrong. Anything you say at the scene can be used by the defense.
Contact a motorcycle accident attorney immediately.
The law is new. Many drivers, police officers, and even some attorneys are not yet familiar with its specific requirements. An attorney who understands SB24-079 can protect your claim from the outset.
SB24-079 expires September 1, 2027 unless the General Assembly acts to extend it. CDOT’s safety report, due before that date, will determine the law’s future. In the meantime, riders who filter legally are fully protected under Colorado law, and drivers who injure them are fully liable.
Frequently Asked Questions: Lane Filtering and Lane Splitting in Colorado
Is lane splitting legal in Colorado?
No. Lane splitting, which involves riding between lanes of moving traffic, is illegal in Colorado. Lane filtering, which allows motorcyclists to pass between lanes of completely stopped traffic at 15 mph or less, became legal on August 7, 2024 under SB24-079. The distinction between the two is critical: if surrounding traffic is moving at any speed, passing between lanes is lane splitting and violates Colorado law.
What are the requirements for legal lane filtering in Colorado?
All of the following must be true simultaneously: all traffic in your lane and adjacent same-direction lanes is completely stopped; the lane is wide enough for safe passage; your speed does not exceed 15 mph; you pass on the left, not the right shoulder; you do not enter oncoming traffic lanes; you are at least 18 with a valid motorcycle endorsement; and you stop filtering and merge back when traffic begins to move. Failure to meet any one of these requirements means the maneuver is not authorized under SB24-079.
Can I be found at fault if I was injured while lane filtering?
If you were filtering in full compliance with SB24-079, you were engaged in a legal maneuver. However, the defense will scrutinize every element of compliance: were you truly at 15 mph or less? Was traffic actually stopped? Were you passing on the left? Under Colorado’s comparative fault system, C.R.S. § 13-21-111, even if some fault is attributed to you, you can recover damages as long as your fault is below 50%. Evidence documenting your compliance is essential.
What if a driver did not know lane filtering was legal and hit me?
A driver’s ignorance of the law does not excuse their negligence. If a driver opens a door, changes lanes, or pulls out without checking for a legally filtering motorcycle, the driver is at fault. The law does not require drivers to anticipate lane filtering, but it does require them to exercise reasonable care when opening doors, changing lanes, and operating a vehicle on public roads.
Will the lane filtering law expire?
SB24-079 includes a sunset provision that repeals the law on September 1, 2027. Before that date, CDOT is required to analyze safety data from the law’s implementation period and report to the General Assembly. The legislature will then decide whether to make lane filtering permanent, modify the law, or allow it to expire. Crashes that occurred during the effective period of the law will be evaluated under the law as it existed at the time of the crash.
Injured While Lane Filtering? We Know This Law.
SB24-079 is less than two years old. Many insurance adjusters, police officers, and defense attorneys are still learning its requirements. Rampart Injury Lawyers understands the precise conditions under which lane filtering is legal in Colorado and how to prove compliance when the defense argues otherwise. If you were injured while filtering through stopped traffic along the I-25 corridor, on Denver’s congested surface streets, or at any intersection in the Colorado Springs metro area, contact us for a free consultation.
The law gave you the right to filter. The driver took it away with a door, a lane change, or a moment of road rage. We put it back.
Related Pages: Motorcycle Accident Resources
- Denver Motorcycle Accident Lawyer
- Colorado Springs Motorcycle Accident Lawyer
- Left-Turn Motorcycle Crashes
- Lane Filtering and Lane Splitting in Colorado
- Motorcycle Accident Settlements in Colorado
- Colorado Motorcycle Helmet Law and Your Case
- Road Rash and Skin Graft Injuries
- Motorcycle vs. Car Accidents: Why the Cases Are Different
Sources and Citations
- Colorado General Assembly, SB24-079 Motorcycle Lane Filtering and Passing
- Colorado State Patrol, Colorado’s Lane Filtering Law Goes into Effect
- CDOT, New lane filtering law protects motorcyclists
- American Motorcyclist Association, The Dos and Don’ts of Colorado’s New Lane-Filtering Law
- UC Berkeley SafeTREC, Motorcycle Lane-splitting and Safety in California
- Travis Legal Offices, Motorcycle Safety: Colorado’s New Law on Lane Filtering
- Colorado Revised Statutes: C.R.S. § 42-4-1503, § 42-4-1207, § 42-4-1007, and § 13-21-111
The information on this page is for general informational purposes only and does not constitute legal advice. Every case is different. Past results do not guarantee future outcomes. Reading this page does not create an attorney-client relationship with Rampart Injury Lawyers. SB24-079 includes a sunset provision and may not be in effect at the time you read this page. Verify current Colorado law with an attorney. If you have been injured in a lane filtering or lane splitting crash, contact us for a free consultation.
