The Arizona left lane law, set out in ARS 28-721, requires any driver moving slower than the surrounding flow of traffic on a multi-lane road to stay in the right lane or as close to the right edge of the road as practical.1Arizona Legislature. Arizona Code 28-721 – Driving on Right Side of Roadway; Driving on Shoulder; Exceptions; Education The left lane is a passing lane, not a travel lane, and sitting in it while faster traffic stacks up behind you is a civil traffic violation.
“Slower Than Traffic” Doesn’t Mean the Speed Limit
This is where most drivers get the rule wrong. ARS 28-721 doesn’t mention the posted speed limit anywhere. The trigger is “less than the normal speed of traffic at the time and place and under the conditions then existing.”1Arizona Legislature. Arizona Code 28-721 – Driving on Right Side of Roadway; Driving on Shoulder; Exceptions; Education If the cars around you are moving faster than you are, the keep-right obligation applies, even if you’re already at the limit.
The practical takeaway: driving the speed limit in the left lane is not a legal shield. If traffic is flowing at 75 and you’re doing 65 in the far left lane, you’re the one who needs to move over.
Signs reading “Slower Traffic Keep Right” reinforce the rule, but the obligation exists whether or not a sign is posted. The law applies on any road divided into two or more clearly marked lanes going the same direction — interstates like I-10 and I-17, state routes, and urban streets with multiple travel lanes each way.
When You Can Legally Use the Left Lane
ARS 28-721 lists specific situations where using the left lane is permitted:
- Passing a slower vehicle traveling the same direction. Once the pass is complete, you’re expected to merge back right.
- Preparing for a left turn at an intersection, private road, or driveway.
- When the right side of the roadway is closed for construction or otherwise obstructed.
- On a road designated and signed for one-way traffic.
Heavy congestion is not on that list. In reality, when every lane is crawling at the same speed, the statute’s “slower than normal traffic” trigger isn’t really activated, because no one is moving faster than anyone else. But the law doesn’t grant an explicit right to sit in the left lane during a traffic jam, so don’t assume congestion is a defense if a lane next to you is actually moving.
Yielding to Emergency Vehicles Overrides the Lane Rules
If an emergency vehicle approaches with lights and sirens, ARS 28-775 requires you to yield the right-of-way, pull to a position parallel to and as close as possible to the right-hand edge or curb of the road, and stop until it passes.2Arizona Legislature. Arizona Code 28-775 – Authorized Emergency Vehicles; Approaching Holding your left lane and hoping the ambulance goes around you is not an option. Failing to yield is a separate, more serious violation than a standard left lane infraction.
What a Left Lane Ticket Costs
A violation of ARS 28-721 is a civil traffic infraction. Arizona’s justice courts set their own fine amounts. The Pinal County Justice Court, as one example, lists violations of ARS 28-721 through 28-736 at $235.3Pinal County Justice Courts. Fine Chart Other courts charge more or less, and surcharges and assessments typically push the total above the base fine.
The Motor Vehicle Division also adds 2 points to your driving record. The violation falls under the catch-all category covering “any other traffic regulation that governs a vehicle moving under its own power.”4Arizona Judicial Branch. MVD and Courts Training Manual
Two points from a single ticket won’t threaten your license on its own. The MVD starts looking at Traffic Survival School or suspension once a driver reaches 8 points within 12 months, with longer suspensions at 13, 18, and 24 points over 12- or 36-month windows.4Arizona Judicial Branch. MVD and Courts Training Manual A left lane ticket matters when it’s stacked on top of a speeding ticket or two.
A Bigger Fine Has Been Proposed but Not Passed
Arizona legislators have tried to attach a dedicated penalty to left lane violations. During the 2025 session, House Bill 2235 proposed new “Left lane for passing only, slow traffic keep right” signs on controlled-access highways and a specific civil penalty for the violation.5Arizona Legislature. HB 2235 – House Bill Summary The introduced version set the penalty at $500, and a later engrossed version lowered it to $200.6Arizona Legislature. HB 2235 – House Bill Summary – House Engrossed The bill did not pass. For now, left lane violations are handled as standard civil traffic infractions.
Fighting a Left Lane Citation
You have the right to request a hearing instead of paying the fine. The deadline to respond is printed on the ticket. Miss it and you can face a default judgment, late fees, and potentially a bench warrant.
The cleanest defense is showing your conduct fit one of the statutory exceptions. If you were passing a slower vehicle, moving into position for a left turn, or driving left because the right side of the road was blocked, the statute itself gives you the justification. Dashcam video, GPS logs showing a lane change, or evidence about road conditions at the time of the stop all help. Judges in civil traffic cases need a reason to dismiss, and “I didn’t realize I was going that slow” is rarely enough.
If the citation came alongside other moving violations, the points question matters as much as the fine. Reviewing your current point total before the hearing tells you whether contesting the ticket, negotiating for defensive driving school, or simply paying is the better call.