Liability for a crash at a malfunctioning traffic signal usually splits along two tracks: fault between the drivers based on whether each one obeyed the rules for the signal condition they faced, and separate potential fault on the government agency that was supposed to keep the signal working. Winning a claim on either track depends on evidence that disappears quickly and procedural deadlines that are much shorter than people expect.
What the Law Required You to Do at the Signal
Fault analysis starts with what each driver was legally supposed to do given what the signal was displaying. Get this wrong and everything downstream collapses.
A completely dark signal is treated as an all-way stop in nearly every state. You must stop at the stop line, or before the crosswalk if there is no line, and yield to any vehicle that arrived first. If two vehicles arrive at the same time, the driver on the right goes first. The rule comes from the Uniform Vehicle Code and has been adopted in some form by most state traffic statutes.
A flashing red signal carries the same legal force as a stop sign. The federal Manual on Uniform Traffic Control Devices states that after stopping at a flashing red, “the right to proceed shall be subject to the rules applicable after making a stop at a STOP sign.”1FHWA. 2009 Edition Chapter 4D – Traffic Control Signal Features Rolling through a flashing red is legally identical to blowing a stop sign.
A flashing yellow is not a free pass. You can proceed without stopping, but you must slow down, watch for hazards, yield to pedestrians in the crosswalk, yield to any vehicle already lawfully in the intersection, and yield to oncoming traffic when turning left.1FHWA. 2009 Edition Chapter 4D – Traffic Control Signal Features Typically the major road gets flashing yellow while the minor road gets flashing red. The MUTCD prohibits flashing yellow from facing conflicting approaches, so you should never see crossing directions both flashing yellow.2FHWA. MUTCD 11th Edition Part 4 If you do, treat it like a dark signal and stop.
One trap worth naming: a signal that works in one direction and is dark in the other. If your approach shows no indication at all, your approach is a stop, even if cross traffic appears to have a working green. Assuming right-of-way because you see no red is a common path to a serious crash.
Fault Between Drivers
A driver who enters a dark intersection without stopping has violated a traffic safety statute. That violation opens the door to negligence per se, a doctrine that treats the breach of a safety law as presumptive negligence. The injured party does not have to separately prove the driver failed to act reasonably; the statutory violation does that work.
Having the better signal does not make you immune. Most states use comparative negligence, which divides financial responsibility by each driver’s share of fault. Blow through a flashing yellow at full speed without scanning the intersection and a jury can assign you a percentage of the blame. Your recovery then shrinks by that percentage. A driver found 20 percent at fault on a $50,000 claim collects $40,000.
The particular comparative negligence system in your state matters more than people realize:
- About 23 states use a 51-percent bar: you recover nothing once your share reaches 51 percent.
- Around 10 states set that cutoff at 50 percent.
- A handful use pure comparative negligence, allowing recovery even at 99 percent fault, reduced accordingly.
- A small number still follow contributory negligence, where any fault at all, even one percent, bars recovery entirely.
The difference between living in a pure comparative state and a contributory negligence state can be the difference between a reduced check and nothing.
When You Can Sue the Government
Suing a city, county, or state agency over a broken signal runs into sovereign immunity, the old rule that the government cannot be sued without its consent. Every state and the federal government have waived that immunity partially through tort claims acts, but the waiver comes with limits that defeat many claims before anyone looks at the merits.
Discretionary Versus Operational
The most important limit is the discretionary function exception. High-level policy choices, like where to install signals, how to budget for maintenance, and which intersections to prioritize, are typically shielded from liability. The Federal Tort Claims Act writes this exception into the statute, barring claims based on the “exercise or performance or the failure to exercise or perform a discretionary function or duty.”3Office of the Law Revision Counsel. 28 USC 2680 – Exceptions State tort claims acts follow a similar pattern.
Once a signal is installed and in service, keeping it working becomes an operational (sometimes called ministerial) task. Failing to fix a signal that the agency knows is broken looks less like a policy choice and more like dropped routine maintenance. That is where claims against government agencies gain traction.
Damage Caps
Even with a winning case on the merits, tort claims acts cap recovery. The caps vary widely. Some states limit recovery to $100,000 per person. Others allow $500,000 or more. A few permit recovery exceeding $1 million per occurrence. Checking your state’s specific cap before investing in litigation is basic due diligence.
Filing Deadlines
Notice-of-claim deadlines are much shorter than ordinary statutes of limitations and inconsistent across states. You may need to submit a formal notice to the government entity in as few as 90 days. Other states allow up to two years. At the federal level, you must file an administrative claim with the responsible agency before suing, and the agency has six months to respond before you can treat silence as a denial and go to court.4Office of the Law Revision Counsel. 28 USC 2675 – Disposition by Federal Agency as Prerequisite Missing the notice deadline is usually a permanent bar, regardless of how strong the underlying case is. This is where most claims die: not on the merits, but on a missed procedural clock.
Proving the Agency Knew
Holding an agency liable generally requires showing it had notice the signal was broken and failed to act within a reasonable time. Notice comes in two forms.
Actual Notice
Actual notice means someone told the agency. A 911 or 311 call, a maintenance work order, a police officer logging the outage, or a citizen complaint on a municipal reporting portal all count. Automated alerts from modern signal controllers qualify too. Written records with timestamps are the strongest evidence because the agency cannot easily dispute them.
Constructive Notice
When nobody reported the problem, you can argue the agency should have known through routine inspection. The FHWA recommends that agencies inspect signals annually or semiannually as part of preventive maintenance.5FHWA. Traffic Signal Program Handbook A signal broken for weeks at an intersection not inspected in over a year supports a constructive notice argument. Power grid outage logs, nearby business security footage, and even timestamped social media posts can establish how long the defect existed.
Reasonable Response Time
Notice alone is not enough. The agency’s response also has to have been unreasonable given the circumstances. A six-hour delay during an ice storm that knocked out signals across a county is probably reasonable. A two-day delay in clear weather with crews available and the outage known starts to look like actionable negligence. Courts weigh the severity of the malfunction, the agency’s resources, and whether a faster temporary fix, like a patrol officer directing traffic or portable stop signs, could have been deployed while a permanent repair was arranged.
One technical point helps on causation: if conflicting greens were displayed in both directions, the signal’s conflict monitor failed. Every traffic signal is required to have an automatic conflict monitor that forces the intersection into flash mode when it detects contradictory indications, and the flash mode cannot be defeated by removing or turning off the controller.2FHWA. MUTCD 11th Edition Part 4 A dual-green scenario points at a maintenance failure rather than a random event.
Evidence to Preserve Immediately
The signal’s condition at the moment of the crash is the single most important fact in the entire case, and it is also the most perishable. A repair crew can restore the signal before anyone records what you saw. What you capture in the first few minutes often decides whether the claim is viable.
- Photograph or video every signal head from your approach, and from the cross-street approach if it is safe to walk over. A dark signal or a flashing pattern is the foundation of the whole case.
- Record the exact time, the weather, lighting conditions, and any visible damage to signal equipment such as downed wires or a tilted pole.
- Get the names and contact information of other drivers and pedestrians who saw the signal before the crash. Their testimony can confirm what your photos alone leave ambiguous.
- Make sure the responding officer documents the signal malfunction in the police report. If they do not, ask them to. Insurers and courts rely heavily on what the report says.
- Request the agency’s maintenance records for that signal, through counsel or a public records request. These records can show prior malfunctions, missed inspections, and repair delays that establish a pattern.
- Ask about traffic camera footage early. Many signalized intersections have cameras, and footage can show exactly what each signal head was displaying before and during the crash. Agencies often overwrite footage on short cycles, so a prompt preservation request matters.
Where government liability is in play, a traffic engineer can review signal timing data, inspect the conflict monitor, and evaluate whether the agency maintained the signal in compliance with MUTCD standards.2FHWA. MUTCD 11th Edition Part 4 An accident reconstruction specialist uses vehicle positions, skid marks, and onboard vehicle data to establish speeds, reaction times, and who actually had the right-of-way. Expert analysis is often what separates a successful claim from one that goes nowhere.
When the Cause Is Not Obvious Right Away
Notice-of-claim deadlines generally start running from the date of the crash. The discovery rule is a narrow exception. Under it, the clock does not start until you knew, or reasonably should have known, that an agency’s negligence caused your injuries. If the signal looked normal from your direction but was sending conflicting indications to cross traffic because of a hidden controller defect, you may not learn the true cause until maintenance records surface weeks or months later. A court may then toll the filing deadline until you had enough information to identify the agency’s role. The rule does not apply automatically, and the burden of showing you could not reasonably have identified the claim earlier is on you. For that reason, treating the shortest plausible deadline as your real deadline is safer than counting on tolling.